diff --git a/sc2/ChangeLog b/sc2/ChangeLog
index c9b9eb054..a351c8d3f 100644
--- a/sc2/ChangeLog
+++ b/sc2/ChangeLog
@@ -1,4 +1,7 @@
 Changes towards version 0.4:
+- Introduced a new synchronization construct (CrossThreadMutex) and 
+  migrated the GraphicsSem and clock_sem over to it (#359) -Michael
+- Replaced thread-local Semaphores with Mutexes (#359) -Michael
 - Load/save icons don't flash anymore when in savegame menu
   (part of bug #291), from Paxtez
 - Savegame slot now defaults to the last one used during one execution
diff --git a/sc2/src/sc2code/battle.c b/sc2/src/sc2code/battle.c
index 97737bd28..3b7caa378 100644
--- a/sc2/src/sc2code/battle.c
+++ b/sc2/src/sc2code/battle.c
@@ -163,7 +163,7 @@ Battle (void)
 	extern SIZE InitShips (void);
 	void UninitShips (void);
 
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 
 	SetResourceIndex (hResIndex);
 
@@ -222,7 +222,7 @@ Battle (void)
 				ScreenTransition (3, &r);
 			}
 			UnbatchGraphics ();
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 			if (nth_frame)
 				TaskSwitch ();
 			else
@@ -231,7 +231,7 @@ Battle (void)
 				NextTime = GetTimeCounter ();
 			}
 			ProcessInput ();
-			SetSemaphore (GraphicsSem);
+			LockCrossThreadMutex (GraphicsLock);
 		} while (GLOBAL (CurrentActivity) & IN_BATTLE);
 
 AbortBattle:
@@ -242,7 +242,7 @@ AbortBattle:
 	UninitShips ();
 	FreeBattleSong ();
 
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 	
 	return (num_ships < 0);
 }
diff --git a/sc2/src/sc2code/border.c b/sc2/src/sc2code/border.c
index c3a0ce969..7b352ceb7 100644
--- a/sc2/src/sc2code/border.c
+++ b/sc2/src/sc2code/border.c
@@ -40,7 +40,7 @@ DrawSISFrame (void)
 {
 	RECT r;
 
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 	SetContext (ScreenContext);
 
 	BatchGraphics ();
@@ -186,6 +186,6 @@ DrawSISFrame (void)
 	ClearSISRect (DRAW_SIS_DISPLAY);
 	UnbatchGraphics ();
 
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 }
 
diff --git a/sc2/src/sc2code/build.c b/sc2/src/sc2code/build.c
index 031201377..7e3226d75 100644
--- a/sc2/src/sc2code/build.c
+++ b/sc2/src/sc2code/build.c
@@ -205,10 +205,10 @@ ActivateStarShip (COUNT which_ship, SIZE state)
 								
 								if (ShipRemoved)
 								{
-									SetSemaphore (GraphicsSem);
+									LockCrossThreadMutex (GraphicsLock);
 									DeltaSISGauges (UNDEFINED_DELTA,
 											UNDEFINED_DELTA, UNDEFINED_DELTA);
-									ClearSemaphore (GraphicsSem);
+									UnlockCrossThreadMutex (GraphicsLock);
 								}
 							}
 						}
@@ -293,10 +293,10 @@ ActivateStarShip (COUNT which_ship, SIZE state)
 								);
 					}
 
-					SetSemaphore (GraphicsSem);
+					LockCrossThreadMutex (GraphicsLock);
 					DeltaSISGauges (UNDEFINED_DELTA,
 							UNDEFINED_DELTA, UNDEFINED_DELTA);
-					ClearSemaphore (GraphicsSem);
+					UnlockCrossThreadMutex (GraphicsLock);
 					return (i);
 				}
 				break;
diff --git a/sc2/src/sc2code/clock.c b/sc2/src/sc2code/clock.c
index 7fdbbc5ce..b49f3f65b 100644
--- a/sc2/src/sc2code/clock.c
+++ b/sc2/src/sc2code/clock.c
@@ -65,7 +65,7 @@ int clock_task_func(void* data)
 				 * can be halted. (e.g. during battle
 				 * or communications)
 				 */
-		SetSemaphore (GLOBAL (GameClock.clock_sem));
+		LockCrossThreadMutex (GLOBAL (GameClock.clock_lock));
 		TimeIn = GetTimeCounter ();
 
 		if (GLOBAL (GameClock).tick_count <= 0
@@ -89,7 +89,7 @@ int clock_task_func(void* data)
 				}
 			}
 
-			SetSemaphore (GraphicsSem);
+			LockCrossThreadMutex (GraphicsLock);
 			DrawStatusMessage (NULL_PTR);
 			{
 				HEVENT hEvent;
@@ -114,7 +114,7 @@ int clock_task_func(void* data)
 					FreeEvent (hEvent);
 				}
 			}
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 		}
 
 		OnAutoPilot = (BOOLEAN)(
@@ -126,7 +126,7 @@ int clock_task_func(void* data)
 		{
 			DWORD num_ticks;
 
-			SetSemaphore (GraphicsSem);
+			LockCrossThreadMutex (GraphicsLock);
 			num_ticks = GetTimeCounter () - LastTime;
 			if (!OnAutoPilot)
 			{
@@ -159,13 +159,13 @@ int clock_task_func(void* data)
 				cycle_index = (cycle_index + 1) % NUM_CYCLES;
 				delay_count = NUM_DELAYS;
 			}
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 
 			LastPilot = OnAutoPilot;
 			LastTime += num_ticks;
 		}
 		
-		ClearSemaphore (GLOBAL (GameClock.clock_sem));
+		UnlockCrossThreadMutex (GLOBAL (GameClock.clock_lock));
 		SleepThreadUntil (TimeIn + ONE_SECOND / 120);
 	}
 	FinishTask (task);
@@ -215,7 +215,7 @@ SuspendGameClock (void)
 	LockMutex (clock_mutex);
 	if (GameClockRunning ())
 	{
-		SetSemaphore (GLOBAL (GameClock.clock_sem));
+		LockCrossThreadMutex (GLOBAL (GameClock.clock_lock));
 		GLOBAL (GameClock.TimeCounter) = 0;
 	}
 	UnlockMutex (clock_mutex);
@@ -228,7 +228,7 @@ ResumeGameClock (void)
 	if (!GameClockRunning ())
 	{
 		GLOBAL (GameClock.TimeCounter) = GetTimeCounter ();
-		ClearSemaphore (GLOBAL (GameClock.clock_sem));
+		UnlockCrossThreadMutex (GLOBAL (GameClock.clock_lock));
 	}
 	UnlockMutex (clock_mutex);
 }
@@ -245,7 +245,7 @@ SetGameClockRate (COUNT seconds_per_day)
 	SIZE new_day_in_ticks, new_tick_count;
 
 //if (GLOBAL (GameClock.clock_sem)) fprintf (stderr, "%u\n", GLOBAL (GameClock.clock_sem));
-	SetSemaphore (GLOBAL (GameClock.clock_sem));
+	LockCrossThreadMutex (GLOBAL (GameClock.clock_lock));
 	new_day_in_ticks = (SIZE)(seconds_per_day * CLOCK_BASE_FRAMERATE);
 	if (GLOBAL (GameClock.day_in_ticks) == 0)
 		new_tick_count = new_day_in_ticks;
@@ -256,7 +256,7 @@ SetGameClockRate (COUNT seconds_per_day)
 		new_tick_count = 1;
 	GLOBAL (GameClock.day_in_ticks) = new_day_in_ticks;
 	GLOBAL (GameClock.tick_count) = new_tick_count;
-	ClearSemaphore (GLOBAL (GameClock.clock_sem));
+	UnlockCrossThreadMutex (GLOBAL (GameClock.clock_lock));
 }
 
 BOOLEAN
diff --git a/sc2/src/sc2code/clock.h b/sc2/src/sc2code/clock.h
index 0c3b4bf3f..b4fcfe232 100644
--- a/sc2/src/sc2code/clock.h
+++ b/sc2/src/sc2code/clock.h
@@ -56,7 +56,7 @@ typedef struct
 	BYTE day_index, month_index;
 	COUNT year_index;
 	SIZE tick_count, day_in_ticks;
-	Semaphore clock_sem;
+	CrossThreadMutex clock_lock;
 	Task clock_task;
 	DWORD TimeCounter;
 
diff --git a/sc2/src/sc2code/comm.c b/sc2/src/sc2code/comm.c
index bf1b6b0fb..9c51fa099 100644
--- a/sc2/src/sc2code/comm.c
+++ b/sc2/src/sc2code/comm.c
@@ -869,10 +869,10 @@ int ambient_anim_task(void* data)
 	while ((CommFrame = CommData.AlienFrame) == 0 && !Task_ReadState (task, TASK_EXIT))
 		TaskSwitch ();
 
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 	memset ((PSTR)&DisplayArray[0], 0, sizeof (DisplayArray));
 	SetUpSequence (Sequencer);
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 
 	ActiveMask = 0;
 	TalkAlarm = 0;
@@ -901,7 +901,7 @@ int ambient_anim_task(void* data)
 
 		SleepThreadUntil (LastTime + ONE_SECOND / 120);
 
-		SetSemaphore (GraphicsSem);
+		LockCrossThreadMutex (GraphicsLock);
 		BatchGraphics ();
 		CurTime = GetTimeCounter ();
 		ElapsedTicks = CurTime - LastTime;
@@ -1287,7 +1287,7 @@ int ambient_anim_task(void* data)
 			UpdateSpeechGraphics (FALSE);
 		}
 		UnbatchGraphics ();
-		ClearSemaphore (GraphicsSem);
+		UnlockCrossThreadMutex (GraphicsLock);
 		xform_PLUT_step(ElapsedTicks);
 	}
 	FinishTask (task);
@@ -1319,15 +1319,15 @@ SpewPhrases (COUNT wait_track)
 		if (wait_track == 1 || wait_track == (COUNT)~0)
 		{
 			ResumeTrack ();
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 			do
 			{
 				TaskSwitch ();
-				SetSemaphore (GraphicsSem);
+				LockCrossThreadMutex (GraphicsLock);
 				which_track = PlayingTrack ();
-				ClearSemaphore (GraphicsSem);
+				UnlockCrossThreadMutex (GraphicsLock);
 			} while (!which_track);
-			SetSemaphore (GraphicsSem);
+			LockCrossThreadMutex (GraphicsLock);
 		}
 	}
 	else if (which_track <= wait_track)
@@ -1338,7 +1338,7 @@ SpewPhrases (COUNT wait_track)
 		if (GLOBAL (CurrentActivity) & CHECK_ABORT)
 			break;
 		
-		ClearSemaphore (GraphicsSem);
+		UnlockCrossThreadMutex (GraphicsLock);
 		/* FIXME: is this a ramnant of 128-tick clock?
 		 * with 120-tick clock this will sleep for 1 tick --
 		 * for 1/120th of a second; if ONE_SECOND is upgraded
@@ -1353,7 +1353,7 @@ SpewPhrases (COUNT wait_track)
 		UpdateInputState ();
 #endif
 
-		SetSemaphore (GraphicsSem);
+		LockCrossThreadMutex (GraphicsLock);
 		if (CurrentMenuState.cancel)
 		{
 			SetSliderImage (SetAbsFrameIndex (ActivityFrame, 8));
@@ -1442,7 +1442,7 @@ AlienTalkSegue (COUNT wait_track)
 	if ((GLOBAL (CurrentActivity) & CHECK_ABORT)
 			|| (CommData.AlienTransitionDesc.AnimFlags & TALK_INTRO))
 		return;
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 
 	if (!pCurInputState->Initialized)
 	{
@@ -1504,9 +1504,9 @@ AlienTalkSegue (COUNT wait_track)
 				pCurInputState->AnimTask = AssignTask (ambient_anim_task,
 						3072, "ambient animations");
 
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 			SleepThreadUntil (TimeOut);
-			SetSemaphore (GraphicsSem);
+			LockCrossThreadMutex (GraphicsLock);
 		}
 
 		LastActivity &= ~CHECK_LOAD;
@@ -1525,9 +1525,9 @@ AlienTalkSegue (COUNT wait_track)
 			CommData.AlienTalkDesc.AnimFlags |= WAIT_TALKING;
 		while (CommData.AlienTalkDesc.AnimFlags & TALK_INTRO)
 		{
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 			TaskSwitch ();
-			SetSemaphore (GraphicsSem);
+			LockCrossThreadMutex (GraphicsLock);
 		}
 	}
 
@@ -1543,7 +1543,7 @@ AlienTalkSegue (COUNT wait_track)
 			CommData.AlienTalkDesc.AnimFlags |= PAUSE_TALKING;
 	}
 
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 	FlushInput ();
 	while (AnyButtonPress (TRUE))
 		TaskSwitch ();
@@ -1578,7 +1578,7 @@ DoCommunication (PENCOUNTER_STATE pES)
 			if (CurrentMenuState.left)
 			{
 				FadeMusic (BACKGROUND_VOL, ONE_SECOND);
-				SetSemaphore (GraphicsSem);
+				LockCrossThreadMutex (GraphicsLock);
 				CommData.AlienTransitionDesc.AnimFlags &= ~(TALK_INTRO | TALK_DONE);
 				if (CommData.AlienTalkDesc.NumFrames)
 				{
@@ -1594,9 +1594,9 @@ DoCommunication (PENCOUNTER_STATE pES)
 						CommData.AlienTalkDesc.AnimFlags |= WAIT_TALKING;
 					while (CommData.AlienTalkDesc.AnimFlags & TALK_INTRO)
 					{
-						ClearSemaphore (GraphicsSem);
+						UnlockCrossThreadMutex (GraphicsLock);
 						TaskSwitch ();
-						SetSemaphore (GraphicsSem);
+						LockCrossThreadMutex (GraphicsLock);
 					}
 				}
 				
@@ -1609,7 +1609,7 @@ DoCommunication (PENCOUNTER_STATE pES)
 						CommData.AlienTalkDesc.AnimFlags |= PAUSE_TALKING;
 				}
 
-				ClearSemaphore (GraphicsSem);
+				UnlockCrossThreadMutex (GraphicsLock);
 				FlushInput ();
 				while (AnyButtonPress (TRUE))
 					TaskSwitch ();
@@ -1631,9 +1631,9 @@ DoCommunication (PENCOUNTER_STATE pES)
 		if (pES->top_response == (BYTE)~0)
 		{
 			pES->top_response = 0;
-			SetSemaphore (GraphicsSem);
+			LockCrossThreadMutex (GraphicsLock);
 			RefreshResponses (pES);
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 		}
 
 		if (CurrentMenuState.select)
@@ -1645,11 +1645,11 @@ DoCommunication (PENCOUNTER_STATE pES)
 					pES->phrase_buf_index);
 			pES->phrase_buf[pES->phrase_buf_index++] = '\0';
 
-			SetSemaphore (GraphicsSem);
+			LockCrossThreadMutex (GraphicsLock);
 			FeedbackPlayerPhrase (pES->phrase_buf);
 			StopTrack ();
 			SetSliderImage (SetAbsFrameIndex (ActivityFrame, 2));
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 
 			FadeMusic (BACKGROUND_VOL, ONE_SECOND);
 
@@ -1676,21 +1676,21 @@ DoCommunication (PENCOUNTER_STATE pES)
 			DWORD CurTime;
 			FONT fLast;
 
-			SetSemaphore (GraphicsSem);
+			LockCrossThreadMutex (GraphicsLock);
 			DrawSISComWindow ();
 			FeedbackPlayerPhrase (pES->phrase_buf);
 			summary = TRUE;
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 			CurTime = GetTimeCounter ();
 			SleepThreadUntil (CurTime + ONE_SECOND / 30);
-			SetSemaphore (GraphicsSem);
+			LockCrossThreadMutex (GraphicsLock);
 			r.corner.x = 0;
 			r.corner.y = 0;
 			r.extent.width = SIS_SCREEN_WIDTH;
 			r.extent.height = SIS_SCREEN_HEIGHT - SLIDER_Y - SLIDER_HEIGHT + 2;
 			SetContextForeGroundColor (BUILD_COLOR (MAKE_RGB15 (0x00, 0x05, 0x00), 0x6E));
 			DrawFilledRectangle (&r);
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 
 			SetContextBackGroundColor (BUILD_COLOR (MAKE_RGB15 (0x00, 0x05, 0x00), 0x6E));
 			SetContextForeGroundColor (BUILD_COLOR (MAKE_RGB15 (0x00, 0x10, 0x00), 0x6B));
@@ -1727,9 +1727,9 @@ DoCommunication (PENCOUNTER_STATE pES)
 					buffer[i] = '\0';
 					temp++;
 					t.pStr = buffer;
-					SetSemaphore (GraphicsSem);
+					LockCrossThreadMutex (GraphicsLock);
 					font_DrawText (&t);
-					ClearSemaphore (GraphicsSem);
+					UnlockCrossThreadMutex (GraphicsLock);
 					t.baseline.y += DELTA_Y_SUMMARY;
 					col++;
 					if (col > MAX_COLS)
@@ -1738,9 +1738,9 @@ DoCommunication (PENCOUNTER_STATE pES)
 						t.align = ALIGN_CENTER;
 						t.pStr = "_MORE_";
 						SetContextForeGroundColor (BUILD_COLOR (MAKE_RGB15 (0x00, 0x17, 0x00), 0x01));
-						SetSemaphore (GraphicsSem);
+						LockCrossThreadMutex (GraphicsLock);
 						font_DrawText (&t);
-						ClearSemaphore (GraphicsSem);
+						UnlockCrossThreadMutex (GraphicsLock);
 						col = 0;
 						t.baseline.x = SAFE_X + 2;
 						t.align = ALIGN_LEFT;
@@ -1748,10 +1748,10 @@ DoCommunication (PENCOUNTER_STATE pES)
 
 						WaitAnyButtonOrQuit (TRUE);
 
-						SetSemaphore (GraphicsSem);
+						LockCrossThreadMutex (GraphicsLock);
 						SetContextForeGroundColor (BUILD_COLOR (MAKE_RGB15 (0x00, 0x05, 0x00), 0x6E));
 						DrawFilledRectangle (&r);
-						ClearSemaphore (GraphicsSem);
+						UnlockCrossThreadMutex (GraphicsLock);
 						SetContextForeGroundColor (BUILD_COLOR (MAKE_RGB15 (0x00, 0x10, 0x00), 0x6B));
 					}
 				}
@@ -1760,9 +1760,9 @@ DoCommunication (PENCOUNTER_STATE pES)
 					break;				
 				
 				t.pStr = temp;
-				SetSemaphore (GraphicsSem);
+				LockCrossThreadMutex (GraphicsLock);
 				font_DrawText (&t);
-				ClearSemaphore (GraphicsSem);
+				UnlockCrossThreadMutex (GraphicsLock);
 				t.baseline.y += DELTA_Y_SUMMARY;
 				col++;
 				if (col > MAX_COLS && curr->next != NULL)
@@ -1772,9 +1772,9 @@ DoCommunication (PENCOUNTER_STATE pES)
 					t.align = ALIGN_CENTER;
 					t.pStr = "_MORE_";
 					SetContextForeGroundColor (BUILD_COLOR (MAKE_RGB15 (0x00, 0x17, 0x00), 0x01));
-					SetSemaphore (GraphicsSem);
+					LockCrossThreadMutex (GraphicsLock);
 					font_DrawText (&t);
-					ClearSemaphore (GraphicsSem);
+					UnlockCrossThreadMutex (GraphicsLock);
 					col = 0;
 					t.baseline.x = SAFE_X + 2;
 					t.align = ALIGN_LEFT;
@@ -1782,22 +1782,22 @@ DoCommunication (PENCOUNTER_STATE pES)
 
 					WaitAnyButtonOrQuit (TRUE);
 
-					SetSemaphore (GraphicsSem);
+					LockCrossThreadMutex (GraphicsLock);
 					SetContextForeGroundColor (BUILD_COLOR (MAKE_RGB15 (0x00, 0x05, 0x00), 0x6E));
 					DrawFilledRectangle (&r);
-					ClearSemaphore (GraphicsSem);
+					UnlockCrossThreadMutex (GraphicsLock);
 					SetContextForeGroundColor (BUILD_COLOR (MAKE_RGB15 (0x00, 0x10, 0x00), 0x6B));
 				}
 			}
 
 			WaitAnyButtonOrQuit (TRUE);
 
-			SetSemaphore (GraphicsSem);
+			LockCrossThreadMutex (GraphicsLock);
 			SetContextFont (fLast);
 			RefreshResponses (pES);
 			SetContextForeGroundColor (BUILD_COLOR (MAKE_RGB15 (0x00, 0x00, 0x00), 0x00));
 			DrawFilledRectangle (&r);
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 			SummaryChange = TRUE;
 			summary = FALSE;
 			FlushInput ();
@@ -1810,7 +1810,7 @@ DoCommunication (PENCOUNTER_STATE pES)
 			if (CurrentMenuState.left)
 			{
 				FadeMusic (BACKGROUND_VOL, ONE_SECOND);
-				SetSemaphore (GraphicsSem);
+				LockCrossThreadMutex (GraphicsLock);
 				FeedbackPlayerPhrase (pES->phrase_buf);
 
 				CommData.AlienTransitionDesc.AnimFlags &= ~(TALK_INTRO | TALK_DONE);
@@ -1828,9 +1828,9 @@ DoCommunication (PENCOUNTER_STATE pES)
 						CommData.AlienTalkDesc.AnimFlags |= WAIT_TALKING;
 					while (CommData.AlienTalkDesc.AnimFlags & TALK_INTRO)
 					{
-						ClearSemaphore (GraphicsSem);
+						UnlockCrossThreadMutex (GraphicsLock);
 						TaskSwitch ();
-						SetSemaphore (GraphicsSem);
+						LockCrossThreadMutex (GraphicsLock);
 					}
 				}
 
@@ -1847,7 +1847,7 @@ DoCommunication (PENCOUNTER_STATE pES)
 					RefreshResponses (pES);
 					FadeMusic (FOREGROUND_VOL, ONE_SECOND);
 				}
-				ClearSemaphore (GraphicsSem);
+				UnlockCrossThreadMutex (GraphicsLock);
 				FlushInput ();
 				while (AnyButtonPress (TRUE))
 					TaskSwitch ();
@@ -1866,7 +1866,7 @@ DoCommunication (PENCOUNTER_STATE pES)
 			{
 				COORD y;
 
-				SetSemaphore (GraphicsSem);
+				LockCrossThreadMutex (GraphicsLock);
 				BatchGraphics ();
 				add_text (-2, &pES->response_list[pES->cur_response].response_text);
 
@@ -1884,20 +1884,20 @@ DoCommunication (PENCOUNTER_STATE pES)
 					RefreshResponses (pES);
 				}
 				UnbatchGraphics ();
-				ClearSemaphore (GraphicsSem);
+				UnlockCrossThreadMutex (GraphicsLock);
 			}
 		}
 		
 		return (TRUE);
 	}
 
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 
 	if (pES->AnimTask)
 	{
-		ClearSemaphore (GraphicsSem);
+		UnlockCrossThreadMutex (GraphicsLock);
 		ConcludeTask (pES->AnimTask);
-		SetSemaphore (GraphicsSem);
+		LockCrossThreadMutex (GraphicsLock);
 		pES->AnimTask = 0;
 	}
 	CommData.AlienTransitionDesc.AnimFlags &= ~(TALK_INTRO | TALK_DONE);
@@ -1906,7 +1906,7 @@ DoCommunication (PENCOUNTER_STATE pES)
 	DestroyContext (ReleaseContext (TaskContext));
 	TaskContext = 0;
 
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 
 	FlushPLUTXForms ();
 	ColorChange = FALSE;
@@ -2020,15 +2020,15 @@ HailAlien (void)
 			if (pMenuState == 0)
 			{
 				RepairSISBorder ();
-				ClearSemaphore (GraphicsSem);
+				UnlockCrossThreadMutex (GraphicsLock);
 				DrawMenuStateStrings ((BYTE)~0, 1);
-				SetSemaphore (GraphicsSem);
+				LockCrossThreadMutex (GraphicsLock);
 			}
 			else /* in starbase */
 			{
-				ClearSemaphore (GraphicsSem);
+				UnlockCrossThreadMutex (GraphicsLock);
 				DrawSISFrame ();
-				SetSemaphore (GraphicsSem);
+				LockCrossThreadMutex (GraphicsLock);
 				if (GET_GAME_STATE (STARBASE_AVAILABLE))
 				{
 					DrawSISMessage (GAME_STRING (STARBASE_STRING_BASE + 1));
@@ -2045,7 +2045,7 @@ HailAlien (void)
 		DrawSISComWindow ();
 	}
 
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 
 	LastActivity |= CHECK_LOAD; /* prevent spurious input */
 	(*CommData.init_encounter_func) ();
@@ -2053,7 +2053,7 @@ HailAlien (void)
 	if (!(GLOBAL (CurrentActivity) & (CHECK_ABORT | CHECK_LOAD)))
 		(*CommData.uninit_encounter_func) ();
 
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 
 	DestroyStringTable (ReleaseStringTable (CommData.ConversationPhrases));
 	DestroyMusic ((MUSIC_REF)CommData.AlienSong);
@@ -2078,7 +2078,7 @@ InitCommunication (RESOURCE which_comm)
 
 	last_subtitle = NULL;
 
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 
 	if (LastActivity & CHECK_LOAD)
 	{
@@ -2087,9 +2087,9 @@ InitCommunication (RESOURCE which_comm)
 		{
 			if (LOBYTE (LastActivity) == 0)
 			{
-				ClearSemaphore (GraphicsSem);
+				UnlockCrossThreadMutex (GraphicsLock);
 				DrawSISFrame ();
-				SetSemaphore (GraphicsSem);
+				LockCrossThreadMutex (GraphicsLock);
 			}
 			else
 			{
@@ -2147,7 +2147,7 @@ InitCommunication (RESOURCE which_comm)
 			CommData = *LocDataPtr;
 	}
 
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 
 	if (GET_GAME_STATE (BATTLE_SEGUE) == 0)
 		status = HAIL;
@@ -2161,7 +2161,7 @@ InitCommunication (RESOURCE which_comm)
 		SET_GAME_STATE (BATTLE_SEGUE, 1);
 	}
 
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 
 	if (status == HAIL)
 	{
@@ -2175,7 +2175,7 @@ InitCommunication (RESOURCE which_comm)
 	SetResourceIndex (hOldIndex);
 	CloseResourceIndex (hIndex);
 
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 
 	status = 0;
 	if (!(GLOBAL (CurrentActivity) & (CHECK_ABORT | CHECK_LOAD)))
diff --git a/sc2/src/sc2code/comm/comandr/comandr.c b/sc2/src/sc2code/comm/comandr/comandr.c
index 95232e2ad..2485e3ab9 100644
--- a/sc2/src/sc2code/comm/comandr/comandr.c
+++ b/sc2/src/sc2code/comm/comandr/comandr.c
@@ -216,10 +216,10 @@ NoRadioactives (RESPONSE_REF R)
 		{
 			NPCPhrase (HERE_IS_A_NEW_LANDER);
 			++GLOBAL_SIS (NumLanders);
-			SetSemaphore (GraphicsSem);
+			LockCrossThreadMutex (GraphicsLock);
 			DrawLanders ();
 			DeltaSISGauges (4, 0, 0);
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 
 			SET_GAME_STATE (LANDERS_LOST, 1);
 		}
@@ -227,26 +227,26 @@ NoRadioactives (RESPONSE_REF R)
 		{
 			NPCPhrase (HERE_IS_ANOTHER_LANDER);
 			++GLOBAL_SIS (NumLanders);
-			SetSemaphore (GraphicsSem);
+			LockCrossThreadMutex (GraphicsLock);
 			DrawLanders ();
 			DeltaSISGauges (4, 0, 0);
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 		}
 		else if (PLAYER_SAID (R, need_fuel))
 		{
 			NPCPhrase (GIVE_FUEL);
-			SetSemaphore (GraphicsSem);
+			LockCrossThreadMutex (GraphicsLock);
 			DeltaSISGauges (0, 5 * FUEL_TANK_SCALE, 0);
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 
 			SET_GAME_STATE (GIVEN_FUEL_BEFORE, 1);
 		}
 		else if (PLAYER_SAID (R, need_fuel_again))
 		{
 			NPCPhrase (GIVE_FUEL_AGAIN);
-			SetSemaphore (GraphicsSem);
+			LockCrossThreadMutex (GraphicsLock);
 			DeltaSISGauges (0, 5 * FUEL_TANK_SCALE, 0);
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 		}
 
 		if (GLOBAL_SIS (ElementAmounts[RADIOACTIVE]))
@@ -284,10 +284,10 @@ AskAfterRadios (RESPONSE_REF R)
 	{
 		NPCPhrase (HERE_IS_A_NEW_LANDER);
 		++GLOBAL_SIS (NumLanders);
-		SetSemaphore (GraphicsSem);
+		LockCrossThreadMutex (GraphicsLock);
 		DrawLanders ();
 		DeltaSISGauges (4, 0, 0);
-		ClearSemaphore (GraphicsSem);
+		UnlockCrossThreadMutex (GraphicsLock);
 
 		SET_GAME_STATE (LANDERS_LOST, 1);
 	}
@@ -295,26 +295,26 @@ AskAfterRadios (RESPONSE_REF R)
 	{
 		NPCPhrase (HERE_IS_ANOTHER_LANDER);
 		++GLOBAL_SIS (NumLanders);
-		SetSemaphore (GraphicsSem);
+		LockCrossThreadMutex (GraphicsLock);
 		DrawLanders ();
 		DeltaSISGauges (4, 0, 0);
-		ClearSemaphore (GraphicsSem);
+		UnlockCrossThreadMutex (GraphicsLock);
 	}
 	else if (PLAYER_SAID (R, need_fuel))
 	{
 		NPCPhrase (GIVE_FUEL);
-		SetSemaphore (GraphicsSem);
+		LockCrossThreadMutex (GraphicsLock);
 		DeltaSISGauges (0, 5 * FUEL_TANK_SCALE, 0);
-		ClearSemaphore (GraphicsSem);
+		UnlockCrossThreadMutex (GraphicsLock);
 
 		SET_GAME_STATE (GIVEN_FUEL_BEFORE, 1);
 	}
 	else if (PLAYER_SAID (R, need_fuel_again))
 	{
 		NPCPhrase (GIVE_FUEL_AGAIN);
-		SetSemaphore (GraphicsSem);
+		LockCrossThreadMutex (GraphicsLock);
 		DeltaSISGauges (0, 5 * FUEL_TANK_SCALE, 0);
-		ClearSemaphore (GraphicsSem);
+		UnlockCrossThreadMutex (GraphicsLock);
 	}
 	else if (PLAYER_SAID (R, where_get_radios))
 	{
@@ -384,10 +384,10 @@ TellMoonBase (RESPONSE_REF R)
 	{
 		NPCPhrase (HERE_IS_A_NEW_LANDER);
 		++GLOBAL_SIS (NumLanders);
-		SetSemaphore (GraphicsSem);
+		LockCrossThreadMutex (GraphicsLock);
 		DrawLanders ();
 		DeltaSISGauges (4, 0, 0);
-		ClearSemaphore (GraphicsSem);
+		UnlockCrossThreadMutex (GraphicsLock);
 
 		SET_GAME_STATE (LANDERS_LOST, 1);
 	}
@@ -395,26 +395,26 @@ TellMoonBase (RESPONSE_REF R)
 	{
 		NPCPhrase (HERE_IS_ANOTHER_LANDER);
 		++GLOBAL_SIS (NumLanders);
-		SetSemaphore (GraphicsSem);
+		LockCrossThreadMutex (GraphicsLock);
 		DrawLanders ();
 		DeltaSISGauges (4, 0, 0);
-		ClearSemaphore (GraphicsSem);
+		UnlockCrossThreadMutex (GraphicsLock);
 	}
 	else if (PLAYER_SAID (R, need_fuel))
 	{
 		NPCPhrase (GIVE_FUEL);
-		SetSemaphore (GraphicsSem);
+		LockCrossThreadMutex (GraphicsLock);
 		DeltaSISGauges (0, 5 * FUEL_TANK_SCALE, 0);
-		ClearSemaphore (GraphicsSem);
+		UnlockCrossThreadMutex (GraphicsLock);
 
 		SET_GAME_STATE (GIVEN_FUEL_BEFORE, 1);
 	}
 	else if (PLAYER_SAID (R, need_fuel_again))
 	{
 		NPCPhrase (GIVE_FUEL_AGAIN);
-		SetSemaphore (GraphicsSem);
+		LockCrossThreadMutex (GraphicsLock);
 		DeltaSISGauges (0, 5 * FUEL_TANK_SCALE, 0);
-		ClearSemaphore (GraphicsSem);
+		UnlockCrossThreadMutex (GraphicsLock);
 	}
 	else if (PLAYER_SAID (R, we_are_here_to_help))
 	{
@@ -576,9 +576,9 @@ GiveRadios (RESPONSE_REF R)
 		NPCPhrase (FUEL_UP1);		
 		AlienTalkSegue (1);
 
-		SetSemaphore (GraphicsSem);
+		LockCrossThreadMutex (GraphicsLock);
 		CommData.AlienAmbientArray[2].AnimFlags |= ANIM_DISABLED;
-		ClearSemaphore (GraphicsSem);
+		UnlockCrossThreadMutex (GraphicsLock);
 
 		XFormPLUT (GetColorMapAddress (
 				SetAbsColorMapIndex (CommData.AlienColorMap, 0)
diff --git a/sc2/src/sc2code/comm/druuge/druugec.c b/sc2/src/sc2code/comm/druuge/druugec.c
index f450d4806..2149c265c 100644
--- a/sc2/src/sc2code/comm/druuge/druugec.c
+++ b/sc2/src/sc2code/comm/druuge/druugec.c
@@ -230,9 +230,9 @@ Buy (RESPONSE_REF Response)
 			NPCPhrase (NOT_ENOUGH_ROOM);
 		else
 		{
-			SetSemaphore (GraphicsSem);
+			LockCrossThreadMutex (GraphicsLock);
 			DeltaSISGauges (-SHIP_CREW_COST, 0, 0);
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 			SlaveryCount += SHIP_CREW_COST;
 			ActivateStarShip (DRUUGE_SHIP, 1);
 
@@ -246,9 +246,9 @@ Buy (RESPONSE_REF Response)
 			NPCPhrase (NOT_ENOUGH_CREW);
 		else
 		{
-			SetSemaphore (GraphicsSem);
+			LockCrossThreadMutex (GraphicsLock);
 			DeltaSISGauges (-ARTIFACT_CREW_COST, 0, 0);
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 			SlaveryCount += ARTIFACT_CREW_COST;
 			SET_GAME_STATE (ROSY_SPHERE_ON_SHIP, 1);
 			SET_GAME_STATE (ROSY_SPHERE, 1);
@@ -262,9 +262,9 @@ Buy (RESPONSE_REF Response)
 			NPCPhrase (NOT_ENOUGH_CREW);
 		else
 		{
-			SetSemaphore (GraphicsSem);
+			LockCrossThreadMutex (GraphicsLock);
 			DeltaSISGauges (-ARTIFACT_CREW_COST, 0, 0);
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 			SlaveryCount += ARTIFACT_CREW_COST;
 			SET_GAME_STATE (ARTIFACT_2_ON_SHIP, 1);
 
@@ -277,9 +277,9 @@ Buy (RESPONSE_REF Response)
 			NPCPhrase (NOT_ENOUGH_CREW);
 		else
 		{
-			SetSemaphore (GraphicsSem);
+			LockCrossThreadMutex (GraphicsLock);
 			DeltaSISGauges (-ARTIFACT_CREW_COST, 0, 0);
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 			SlaveryCount += ARTIFACT_CREW_COST;
 			SET_GAME_STATE (ARTIFACT_3_ON_SHIP, 1);
 
@@ -293,10 +293,10 @@ Buy (RESPONSE_REF Response)
 			NPCPhrase (NOT_ENOUGH_CREW);
 		else
 		{
-			SetSemaphore (GraphicsSem);
+			LockCrossThreadMutex (GraphicsLock);
 			DeltaSISGauges (-FUEL_CREW_COST,
 					FUEL_CREW_COST * FUEL_TANK_SCALE, 0);
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 			SlaveryCount += FUEL_CREW_COST;
 
 			NPCPhrase (BOUGHT_FUEL);
@@ -452,14 +452,14 @@ DoTransaction (RESPONSE_REF R)
 			capacity -= GLOBAL_SIS (FuelOnBoard);
 			f = (COUNT)((capacity + (FUEL_TANK_SCALE >> 1)) / FUEL_TANK_SCALE);
 
-			SetSemaphore (GraphicsSem);
+			LockCrossThreadMutex (GraphicsLock);
 			while (capacity > 0x3FFFL)
 			{
 				DeltaSISGauges (0, 0x3FFF, 0);
 				capacity -= 0x3FFF;
 			}
 			DeltaSISGauges (0, (SIZE)capacity, 0);
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 
 			NPCPhrase (FUEL0);
 			NPCPhrase (-(int)f);
diff --git a/sc2/src/sc2code/comm/melnorm/melnorm.c b/sc2/src/sc2code/comm/melnorm/melnorm.c
index 919151861..1d62493c3 100644
--- a/sc2/src/sc2code/comm/melnorm/melnorm.c
+++ b/sc2/src/sc2code/comm/melnorm/melnorm.c
@@ -250,9 +250,9 @@ StripShip (COUNT fuel_required)
 	if (fuel_required == 0)
 	{
 		GlobData.SIS_state = SIS_copy;
-		SetSemaphore (GraphicsSem);
+		LockCrossThreadMutex (GraphicsLock);
 		DeltaSISGauges (UNDEFINED_DELTA, rescue_fuel, UNDEFINED_DELTA);
-		ClearSemaphore (GraphicsSem);
+		UnlockCrossThreadMutex (GraphicsLock);
 	}
 	else if (fuel_required == (COUNT)~0)
 	{
@@ -276,9 +276,9 @@ StripShip (COUNT fuel_required)
 				GLOBAL_SIS (ModuleSlots[i]) = EMPTY_SLOT + 2;
 		}
 
-		SetSemaphore (GraphicsSem);
+		LockCrossThreadMutex (GraphicsLock);
 		DeltaSISGauges (UNDEFINED_DELTA, UNDEFINED_DELTA, UNDEFINED_DELTA);
-		ClearSemaphore (GraphicsSem);
+		UnlockCrossThreadMutex (GraphicsLock);
 	}
 	else if (fuel_required)
 	{
@@ -384,9 +384,9 @@ StripShip (COUNT fuel_required)
 		if (total == 0)
 		{
 			NPCPhrase (CHARITY);
-			SetSemaphore (GraphicsSem);
+			LockCrossThreadMutex (GraphicsLock);
 			DeltaSISGauges (0, fuel_required, 0);
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 			return (FALSE);
 		}
 		else
@@ -567,9 +567,9 @@ DeltaCredit (SIZE delta_credit)
 		Credit += delta_credit;
 		SET_GAME_STATE (MELNORME_CREDIT0, LOBYTE (Credit));
 		SET_GAME_STATE (MELNORME_CREDIT1, HIBYTE (Credit));
-		SetSemaphore (GraphicsSem);
+		LockCrossThreadMutex (GraphicsLock);
 		DrawStatusMessage ((UNICODE *)~0);
-		ClearSemaphore (GraphicsSem);
+		UnlockCrossThreadMutex (GraphicsLock);
 	}
 	else
 	{
@@ -810,14 +810,14 @@ DoBuy (RESPONSE_REF R)
 				NPCPhrase (GOT_FUEL);
 
 				f = (DWORD)needed_credit * FUEL_TANK_SCALE;
-				SetSemaphore (GraphicsSem);
+				LockCrossThreadMutex (GraphicsLock);
 				while (f > 0x3FFFL)
 				{
 					DeltaSISGauges (0, 0x3FFF, 0);
 					f -= 0x3FFF;
 				}
 				DeltaSISGauges (0, (SIZE)f, 0);
-				ClearSemaphore (GraphicsSem);
+				UnlockCrossThreadMutex (GraphicsLock);
 			}
 			needed_credit *= (BIO_CREDIT_VALUE / 2);
 		}
@@ -1204,9 +1204,9 @@ DoSell (RESPONSE_REF R)
 			} while (GLOBAL_SIS (TotalBioMass));
 			SleepThread (ONE_SECOND / 2);
 
-			SetSemaphore (GraphicsSem);
+			LockCrossThreadMutex (GraphicsLock);
 			ClearSISRect (DRAW_SIS_DISPLAY);
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 		}
 		else /* if (R == sell_rainbow_locations) */
 		{
@@ -1836,9 +1836,9 @@ Intro (void)
 static COUNT
 uninit_melnorme (void)
 {
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 	DrawStatusMessage (0);
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 
 	return (0);
 }
diff --git a/sc2/src/sc2code/comm/slyland/slyland.c b/sc2/src/sc2code/comm/slyland/slyland.c
index d42cd2830..9951cdccb 100644
--- a/sc2/src/sc2code/comm/slyland/slyland.c
+++ b/sc2/src/sc2code/comm/slyland/slyland.c
@@ -208,9 +208,9 @@ CombatIsInevitable (RESPONSE_REF R)
 
 		NPCPhrase (DESTRUCT_SEQUENCE);
 
-		SetSemaphore (GraphicsSem);
+		LockCrossThreadMutex (GraphicsLock);
 		DeltaSISGauges (0, 0, race_bounty[SLYLANDRO_SHIP] >> 3);
-		ClearSemaphore (GraphicsSem);
+		UnlockCrossThreadMutex (GraphicsLock);
 		SET_GAME_STATE (BATTLE_SEGUE, 0);
 	}
 	else
diff --git a/sc2/src/sc2code/comm/starbas/starbas.c b/sc2/src/sc2code/comm/starbas/starbas.c
index 225df1983..ecae522a0 100644
--- a/sc2/src/sc2code/comm/starbas/starbas.c
+++ b/sc2/src/sc2code/comm/starbas/starbas.c
@@ -1654,9 +1654,9 @@ NormalStarbase (RESPONSE_REF R)
 			NPCPhrase (GLOBAL_SHIP_NAME);
 			NPCPhrase (STARBASE_IS_READY_C);
 
-			SetSemaphore (GraphicsSem);
+			LockCrossThreadMutex (GraphicsLock);
 			DeltaSISGauges (0, 0, 2500);
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 			SET_GAME_STATE (STARBASE_MONTH,
 					GLOBAL (GameClock.month_index));
 			SET_GAME_STATE (STARBASE_DAY,
@@ -1765,9 +1765,9 @@ SellMinerals (RESPONSE_REF R)
 					Sleepy = FALSE;
 					GLOBAL_SIS (ElementAmounts[i]) = 0;
 					GLOBAL_SIS (TotalElementMass) -= amount;
-					SetSemaphore (GraphicsSem);
+					LockCrossThreadMutex (GraphicsLock);
 					DeltaSISGauges (0, 0, amount * GLOBAL (ElementWorth[i]));
-					ClearSemaphore (GraphicsSem);
+					UnlockCrossThreadMutex (GraphicsLock);
 					break;
 				}
 				
@@ -1776,10 +1776,10 @@ SellMinerals (RESPONSE_REF R)
 				TaskSwitch ();
 				TimeIn = GetTimeCounter ();
 				DrawCargoStrings ((BYTE)i, (BYTE)i);
-				SetSemaphore (GraphicsSem);
+				LockCrossThreadMutex (GraphicsLock);
 				ShowRemainingCapacity ();
 				DeltaSISGauges (0, 0, GLOBAL (ElementWorth[i]));
-				ClearSemaphore (GraphicsSem);
+				UnlockCrossThreadMutex (GraphicsLock);
 			} while (--amount);
 		}
 		if (Sleepy) {
@@ -1789,9 +1789,9 @@ SellMinerals (RESPONSE_REF R)
 	}
 	SleepThread (ONE_SECOND / 2);
 
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 	ClearSISRect (DRAW_SIS_DISPLAY);
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 // DrawStorageBays (FALSE);
 
 	if (total < 1000)
diff --git a/sc2/src/sc2code/confirm.c b/sc2/src/sc2code/confirm.c
index 777fd96fd..f040ed847 100644
--- a/sc2/src/sc2code/confirm.c
+++ b/sc2/src/sc2code/confirm.c
@@ -105,7 +105,7 @@ DoConfirmExit (void)
 	if (CommData.ConversationPhrases && PlayingTrack ())
 		PauseTrack ();
 
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 	if (in_confirm)
 	{
 		result = FALSE;
@@ -131,12 +131,12 @@ DoConfirmExit (void)
 
 		DrawConfirmationWindow (response);
 
-		// Releasing the Semaphore lets the rotate_planet_task
+		// Releasing the lock lets the rotate_planet_task
 		// draw a frame.  PauseRotate can still allow one more frame
-		// to be drawn, so it is safer to just not release the Semaphore
-		//ClearSemaphore (GraphicsSem);
+		// to be drawn, so it is safer to just not release the lock
+		//UnlockCrossThreadMutex (GraphicsLock);
 		FlushGraphics ();
-		//SetSemaphore (GraphicsSem);
+		//LockCrossThreadMutex (GraphicsLock);
 
 		GLOBAL (CurrentActivity) |= CHECK_ABORT;
 		FlushInput ();
@@ -181,7 +181,7 @@ DoConfirmExit (void)
 		FlushInput ();
 		SetContext (oldContext);
 	}
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 
 	if (LOBYTE (GLOBAL (CurrentActivity)) != SUPER_MELEE)
 		ResumeGameClock ();
diff --git a/sc2/src/sc2code/credits.c b/sc2/src/sc2code/credits.c
index bf4847680..f7a1bd3c2 100644
--- a/sc2/src/sc2code/credits.c
+++ b/sc2/src/sc2code/credits.c
@@ -54,7 +54,7 @@ Credits (void)
 	if (hMusic)
 		PlayMusic (hMusic, TRUE, 1);
 
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 	SetContext (ScreenContext);
 	GetContextClipRect (&r);
 	s.origin.x = s.origin.y = 0;
@@ -81,19 +81,19 @@ Credits (void)
 		UnbatchGraphics ();
 		DestroyDrawable (ReleaseDrawable (f[i]));
 		
-		ClearSemaphore (GraphicsSem);
+		UnlockCrossThreadMutex (GraphicsLock);
 		while ((GetTimeCounter () - TimeIn < ONE_SECOND * 5) &&
 			!(GLOBAL (CurrentActivity) & CHECK_ABORT))
 		{
 			UpdateInputState ();
 			SleepThreadUntil (ONE_SECOND / 20);
 		}
-		SetSemaphore (GraphicsSem);
+		LockCrossThreadMutex (GraphicsLock);
 		TimeIn = GetTimeCounter ();
 	}
 	
 	DestroyDrawable (ReleaseDrawable (f[0]));
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 
 	WaitAnyButtonOrQuit (FALSE);
 	
@@ -139,7 +139,7 @@ OutTakes (void)
 	optSubtitles = TRUE;
 	sliderDisabled = TRUE;
 
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 	SetContext (ScreenContext);
 	SetContextForeGroundColor (BUILD_COLOR (MAKE_RGB15 (0x0, 0x0, 0x0), 0x00));
 	fade_buf[0] = FadeAllToColor;
@@ -149,7 +149,7 @@ OutTakes (void)
 	r.extent.width = SCREEN_WIDTH;
 	r.extent.height = SCREEN_HEIGHT;
 	DrawFilledRectangle (&r);	
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 
 	for (i = 0; (i < NUM_OUTTAKES) &&
 			!(GLOBAL (CurrentActivity) & CHECK_ABORT); i++)
diff --git a/sc2/src/sc2code/encount.c b/sc2/src/sc2code/encount.c
index 9c0675235..455026ced 100644
--- a/sc2/src/sc2code/encount.c
+++ b/sc2/src/sc2code/encount.c
@@ -47,9 +47,9 @@ DoSelectAction (PMENU_STATE pMS)
 				if (pMS->Initialized)
 				{
 					DrawMenuStateStrings (PM_CONVERSE, pMS->CurState);
-					SetSemaphore (GraphicsSem);
+					LockCrossThreadMutex (GraphicsLock);
 					SetFlashRect ((PRECT)~0L, (FRAME)0);
-					ClearSemaphore (GraphicsSem);
+					UnlockCrossThreadMutex (GraphicsLock);
 				}
 				return ((BOOLEAN)pMS->Initialized);
 			default:
@@ -173,7 +173,7 @@ InitEncounter (void)
 	extern FRAME planet[];
 	MUSIC_REF MR;
 
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 
 	hOldIndex = SetResourceIndex (hResIndex);
 
@@ -183,12 +183,12 @@ InitEncounter (void)
 	MR = LoadMusicInstance (REDALERT_MUSIC);
 	PlayMusic (MR, FALSE, 1);
 	SegueFrame = CaptureDrawable (LoadGraphic (SEGUE_PMAP_ANIM));
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 	while (PLRPlaying (MR))
 		TaskSwitch ();
 	StopMusic ();
 	DestroyMusic (MR);
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 	s.origin.x = s.origin.y = 0;
 
 	SetTransitionSource (NULL);
@@ -300,7 +300,7 @@ InitEncounter (void)
 
 	SetResourceIndex (hOldIndex);
 
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 
 	{
 		MENU_STATE MenuState;
@@ -309,15 +309,15 @@ InitEncounter (void)
 		MenuState.Initialized = FALSE;
 
 		DrawMenuStateStrings (PM_CONVERSE, MenuState.CurState = HAIL);
-		SetSemaphore (GraphicsSem);
+		LockCrossThreadMutex (GraphicsLock);
 		SetFlashRect ((PRECT)~0L, (FRAME)0);
-		ClearSemaphore (GraphicsSem);
+		UnlockCrossThreadMutex (GraphicsLock);
 
 		DoInput ((PVOID)&MenuState, TRUE);
 
-		SetSemaphore (GraphicsSem);
+		LockCrossThreadMutex (GraphicsLock);
 		SetFlashRect (NULL_PTR, (FRAME)0);
-		ClearSemaphore (GraphicsSem);
+		UnlockCrossThreadMutex (GraphicsLock);
 
 		return (MenuState.CurState);
 	}
@@ -357,10 +357,10 @@ DrawFadeText (UNICODE *str1, UNICODE *str2, BOOLEAN fade_in, PRECT
 	{
 		for (i = 0; i < (SIZE) NUM_FADES; ++i)
 		{
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 			if (AnyButtonPress (TRUE))
 				i = NUM_FADES - 1;
-			SetSemaphore (GraphicsSem);
+			LockCrossThreadMutex (GraphicsLock);
 
 			SetContextForeGroundColor (fade_cycle[i]);
 			font_DrawText (&t1);
@@ -373,10 +373,10 @@ DrawFadeText (UNICODE *str1, UNICODE *str2, BOOLEAN fade_in, PRECT
 	{
 		for (i = NUM_FADES - 1; i >= 0; --i)
 		{
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 			if (AnyButtonPress (TRUE))
 				i = 0;
-			SetSemaphore (GraphicsSem);
+			LockCrossThreadMutex (GraphicsLock);
 
 			SetContextForeGroundColor (fade_cycle[i]);
 			font_DrawText (&t1);
@@ -397,7 +397,7 @@ UninitEncounter (void)
 
 	ships_killed = 0;
 
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 	free_gravity_well ();
 
 	if ((GLOBAL (CurrentActivity) & (CHECK_ABORT | CHECK_LOAD))
@@ -478,9 +478,9 @@ UninitEncounter (void)
 					VictoryState = 0;
 				else
 				{
-					ClearSemaphore (GraphicsSem);
+					UnlockCrossThreadMutex (GraphicsLock);
 					DrawSISFrame ();
-					SetSemaphore (GraphicsSem);
+					LockCrossThreadMutex (GraphicsLock);
 
 					DrawSISMessage (NULL_PTR);
 					if (LOBYTE (GLOBAL (CurrentActivity)) == IN_HYPERSPACE)
@@ -601,9 +601,9 @@ UninitEncounter (void)
 								Time = GetTimeCounter ();
 								for (j = 0; j < NUM_SHIP_FADES; ++j)
 								{
-									ClearSemaphore (GraphicsSem);
+									UnlockCrossThreadMutex (GraphicsLock);
 									Sleepy = (BOOLEAN)!AnyButtonPress (TRUE);
-									SetSemaphore (GraphicsSem);
+									LockCrossThreadMutex (GraphicsLock);
 									if (!Sleepy)
 										break;
 
@@ -637,10 +637,10 @@ UninitEncounter (void)
 
 			FlushInput ();
 			Time = GetTimeCounter () + (ONE_SECOND * 3);
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 			while (!(AnyButtonPress (TRUE)) && GetTimeCounter () < Time)
 				TaskSwitch ();
-			SetSemaphore (GraphicsSem);
+			LockCrossThreadMutex (GraphicsLock);
 			if (!CurrentInputState.p1_escape)
 			{
 				DrawFadeText (str1, str2, FALSE, &scavenge_r);
@@ -668,11 +668,11 @@ UninitEncounter (void)
 							&scavenge_r
 							);
 					Time = GetTimeCounter () + ONE_SECOND * 2;
-					ClearSemaphore (GraphicsSem);
+					UnlockCrossThreadMutex (GraphicsLock);
 					while (!(AnyButtonPress (TRUE))
 							&& GetTimeCounter () < Time)
 						TaskSwitch ();
-					SetSemaphore (GraphicsSem);
+					LockCrossThreadMutex (GraphicsLock);
 					if (!CurrentInputState.p1_escape)
 						DrawFadeText (str1, str2, FALSE, &scavenge_r);
 				}
@@ -691,7 +691,7 @@ UninitEncounter (void)
 		}
 	}
 ExitUninitEncounter:
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 
 	return (ships_killed);
 }
@@ -705,7 +705,7 @@ EncounterBattle (void)
 	extern BOOLEAN LoadSC2Data (void);
 	extern BOOLEAN FreeSC2Data (void);
 
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 
 	SET_GAME_STATE (BATTLE_SEGUE, 1);
 
@@ -741,9 +741,9 @@ EncounterBattle (void)
 
 	GameSounds = CaptureSound (LoadSound (GAME_SOUNDS));
 
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 	Battle ();
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 
 	DestroySound (ReleaseSound (GameSounds));
 	GameSounds = 0;
@@ -769,6 +769,6 @@ EncounterBattle (void)
 
 	SetResourceIndex (hLastIndex);
 
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 }
 
diff --git a/sc2/src/sc2code/fmv.c b/sc2/src/sc2code/fmv.c
index 171c9a928..169a2c9b2 100644
--- a/sc2/src/sc2code/fmv.c
+++ b/sc2/src/sc2code/fmv.c
@@ -79,13 +79,13 @@ Introduction (void)
 	xform_buf[0] = FadeAllToBlack;
 	SleepThreadUntil (XFormColorMap (
 			(COLORMAPPTR) xform_buf, ONE_SECOND / 120));
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 	SetContext (ScreenContext);
 	s.origin.x = s.origin.y = 0;
 	s.frame = CaptureDrawable (LoadGraphic (TITLE_ANIM));
 	DrawStamp (&s);
 	DestroyDrawable (ReleaseDrawable (s.frame));
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 
 	xform_buf[0] = FadeAllToColor;
 	TimeOut = XFormColorMap ((COLORMAPPTR)xform_buf, ONE_SECOND / 2);
diff --git a/sc2/src/sc2code/gameopt.c b/sc2/src/sc2code/gameopt.c
index e132c397e..11eee8deb 100644
--- a/sc2/src/sc2code/gameopt.c
+++ b/sc2/src/sc2code/gameopt.c
@@ -163,9 +163,9 @@ FeedbackSetting (BYTE which_setting)
 			break;
 	}
 
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 	DrawStatusMessage (buf);
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 }
 static void 
 FeedbackQuit (BYTE which_setting)
@@ -182,9 +182,9 @@ FeedbackQuit (BYTE which_setting)
 			break;
 	}
 
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 	DrawStatusMessage (buf);
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 }
 
 static BOOLEAN DoSettings (PMENU_STATE pMS);
@@ -199,7 +199,7 @@ DrawDescriptionString (PMENU_STATE pMS, COUNT which_string, SIZE state)
 	FONT Font;
 	static BOOLEAN DoNaming (PMENU_STATE pMS);
 
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 
 	rel_index = (COUNT)(which_string - pMS->first_item.y);
 
@@ -276,7 +276,7 @@ DrawDescriptionString (PMENU_STATE pMS, COUNT which_string, SIZE state)
 		TextRect (&lf, &text_r, char_deltas);
 		if ((text_r.extent.width + 2) >= r.extent.width)
 		{
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 			return (FALSE);
 		}
 
@@ -310,7 +310,7 @@ DrawDescriptionString (PMENU_STATE pMS, COUNT which_string, SIZE state)
 		SetFlashRect (&r, (FRAME)0);
 	}
 
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 	return (TRUE);
 }
 
@@ -436,9 +436,9 @@ DoNaming (PMENU_STATE pMS)
 		pMS->CurString = (STRING)&GD[0];
 		DrawDescriptionString (pMS, pMS->CurState, 1);
 
-		SetSemaphore (GraphicsSem);
+		LockCrossThreadMutex (GraphicsLock);
 		DrawStatusMessage (GAME_STRING (NAMING_STRING_BASE + 0));
-		ClearSemaphore (GraphicsSem);
+		UnlockCrossThreadMutex (GraphicsLock);
 
 		EnableCharacterMode ();
 		DoInput (pMS, TRUE);
@@ -513,9 +513,9 @@ DoSettings (PMENU_STATE pMS)
 			|| (CurrentMenuState.select
 			&& pMS->CurState == EXIT_MENU_SETTING))
 	{
-		SetSemaphore (GraphicsSem);
+		LockCrossThreadMutex (GraphicsLock);
 		DrawStatusMessage (NULL_PTR);
-		ClearSemaphore (GraphicsSem);
+		UnlockCrossThreadMutex (GraphicsLock);
 
 		pMS->CurState = SETTINGS;
 		pMS->InputFunc = DoGameOptions;
@@ -582,9 +582,9 @@ DoQuitMenu (PMENU_STATE pMS)
 			|| (CurrentMenuState.select
 			&& pMS->CurState == NO_QUIT_MENU))
 	{
-		SetSemaphore (GraphicsSem);
+		LockCrossThreadMutex (GraphicsLock);
 		DrawStatusMessage (NULL_PTR);
-		ClearSemaphore (GraphicsSem);
+		UnlockCrossThreadMutex (GraphicsLock);
 
 		pMS->CurState = QUIT_GAME;
 		pMS->InputFunc = DoGameOptions;
@@ -858,9 +858,9 @@ ShowSummary (SUMMARY_DESC *pSD)
 			r.corner.y = SIS_ORG_Y + 84;
 			r.extent = OldRect.extent;
 			SetContextClipRect (&r);
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 			InitLander ((unsigned char)(pSD->Flags | OVERRIDE_LANDER_FLAGS));
-			SetSemaphore (GraphicsSem);
+			LockCrossThreadMutex (GraphicsLock);
 			SetContextClipRect (&OldRect);
 			SetContext (SpaceContext);
 
@@ -1002,7 +1002,7 @@ DoPickGame (PMENU_STATE pMS)
 			pMS->ModuleFrame = SetAbsFrameIndex (PlayFrame, 41);
 		}
 
-		SetSemaphore (GraphicsSem);
+		LockCrossThreadMutex (GraphicsLock);
 		SetTransitionSource (NULL);
 		BatchGraphics ();
 Restart:
@@ -1037,7 +1037,7 @@ Restart:
 		prev_save = pMS->CurState;
 		if (pMS->delta_item == SAVE_GAME || pSD->year_index)
 		{
-			SetSemaphore (GraphicsSem);
+			LockCrossThreadMutex (GraphicsLock);
 			if (pMS->delta_item == SAVE_GAME)
 			{
 				STAMP MsgStamp;
@@ -1056,13 +1056,13 @@ Restart:
 					SetFlashRect (NULL_PTR, (FRAME)0);
 					DrawStamp (&MsgStamp);
 					DestroyDrawable (ReleaseDrawable (MsgStamp.frame));
-					ClearSemaphore (GraphicsSem);
+					UnlockCrossThreadMutex (GraphicsLock);
 					
 					SaveProblem ();
 
 					pMS->Initialized = FALSE;
 					NewState = pMS->CurState;
-					SetSemaphore (GraphicsSem);
+					LockCrossThreadMutex (GraphicsLock);
 					BatchGraphics ();
 					goto Restart;
 				}
@@ -1088,7 +1088,7 @@ Restart:
 					GLOBAL (CurrentActivity) |= CHECK_LOAD;
 			}
 			SetFlashRect (NULL_PTR, (FRAME)0);
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 
 			pMS->ModuleFrame = 0;
 			pMS->CurState = (BYTE)pMS->delta_item;
@@ -1137,7 +1137,7 @@ Restart:
 			TEXT t;
 			BYTE i, SHIFT;
 			UNICODE buf[80],buf2[15];
-			SetSemaphore (GraphicsSem);
+			LockCrossThreadMutex (GraphicsLock);
 
 			BatchGraphics ();
 			if (((SUMMARY_DESC *)pMS->CurString)[NewState].year_index != 0)
@@ -1243,7 +1243,7 @@ ChangeGameSelection:
 				font_DrawText (&t);
 			}
 			SetFlashRect (0, (FRAME)0);
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 		}
 	}
 
@@ -1266,7 +1266,7 @@ PickGame (PMENU_STATE pMS)
 		TaskSwitch ();
 	}
 
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 	OldContext = SetContext (SpaceContext);
 
 	DlgStamp.origin.x = 0;
@@ -1282,11 +1282,11 @@ PickGame (PMENU_STATE pMS)
 	pMS->Initialized = FALSE;
 	pMS->InputFunc = DoPickGame;
 	pMS->CurString = (STRING)&desc_array[0];
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 
 	DoInput (pMS, TRUE);
 
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 	pMS->Initialized = -1;
 	pMS->InputFunc = DoGameOptions;
 
@@ -1338,7 +1338,7 @@ PickGame (PMENU_STATE pMS)
 	DestroyDrawable (ReleaseDrawable (DlgStamp.frame));
 
 	SetContext (OldContext);
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 
 	return (retval);
 }
diff --git a/sc2/src/sc2code/hyper.c b/sc2/src/sc2code/hyper.c
index b1a0514f0..182fabe17 100644
--- a/sc2/src/sc2code/hyper.c
+++ b/sc2/src/sc2code/hyper.c
@@ -322,9 +322,9 @@ LoadHyperspace (void)
 	{
 		if (LOBYTE (LastActivity) == 0)
 		{
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 			DrawSISFrame ();
-			SetSemaphore (GraphicsSem);
+			LockCrossThreadMutex (GraphicsLock);
 		}
 		else
 		{
@@ -360,9 +360,9 @@ LoadHyperspace (void)
 BOOLEAN
 FreeHyperspace (void)
 {
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 	SuspendGameClock ();
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 
 	{
 		FRAME F;
@@ -1601,7 +1601,7 @@ UnbatchGraphics ();
 	OldContext = SetContext (SpaceContext);
 	OldColor = SetContextBackGroundColor (BLACK_COLOR);
 
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 	SuspendGameClock ();
 
 	memset ((PMENU_STATE)&MenuState, 0, sizeof (MenuState));
@@ -1610,13 +1610,13 @@ UnbatchGraphics ();
 	MenuState.CurState = STARMAP + 1;
 
 	DrawMenuStateStrings (PM_STARMAP, STARMAP);
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 	SetFlashRect ((PRECT)~0L, (FRAME)0);
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 
 	DoInput ((PVOID)&MenuState, TRUE);
 
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 	SetFlashRect (NULL_PTR, (FRAME)0);
 
 	SetContext (SpaceContext);
@@ -1624,10 +1624,10 @@ UnbatchGraphics ();
 	if (!(GLOBAL (CurrentActivity) & (CHECK_ABORT | CHECK_LOAD)))
 	{
 		ClearSISRect (CLEAR_SIS_RADAR);
-		ClearSemaphore (GraphicsSem);
+		UnlockCrossThreadMutex (GraphicsLock);
 		WaitForNoInput (ONE_SECOND / 2);
 		ResumeGameClock ();
-		SetSemaphore (GraphicsSem);
+		LockCrossThreadMutex (GraphicsLock);
 	}
 
 	SetContextBackGroundColor (OldColor);
diff --git a/sc2/src/sc2code/init.c b/sc2/src/sc2code/init.c
index e8e387dc2..57b9c6509 100644
--- a/sc2/src/sc2code/init.c
+++ b/sc2/src/sc2code/init.c
@@ -270,8 +270,12 @@ InitGlobData (void)
 	GLOBAL (DisplayArray) = DisplayArray;
 	// The clock semaphore was initially initialized as '1'
 	// but it is always cleared before set, so it toggled between
-	// 2 and 1, which doesn't actually do anything
-	GLOBAL (GameClock.clock_sem) = CreateSemaphore(0,  "Clock");
+	// 2 and 1, which doesn't actually do anything.  When this
+	// was transformed into a mutex, we lock it first to prevent
+	// double-unlock.
+
+	GLOBAL (GameClock.clock_lock) = CreateCrossThreadMutex("Clock");
+	LockCrossThreadMutex (GLOBAL (GameClock.clock_lock));
 }
 
 int
diff --git a/sc2/src/sc2code/intro.c b/sc2/src/sc2code/intro.c
index 82d4a02f0..4b8740741 100644
--- a/sc2/src/sc2code/intro.c
+++ b/sc2/src/sc2code/intro.c
@@ -50,13 +50,13 @@ Introduction (void)
 	xform_buf[0] = FadeAllToBlack;
 	SleepThreadUntil (XFormColorMap (
 			(COLORMAPPTR)xform_buf, ONE_SECOND / 120));
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 	SetContext (ScreenContext);
 	s.origin.x = s.origin.y = 0;
 	s.frame = CaptureDrawable (LoadGraphic (TITLE_ANIM));
 	DrawStamp (&s);
 	DestroyDrawable (ReleaseDrawable (s.frame));
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 
 	FlushInput ();
 
diff --git a/sc2/src/sc2code/libs/graphics/sdl/dcqueue.c b/sc2/src/sc2code/libs/graphics/sdl/dcqueue.c
index 35c7093a9..7b3e2bef7 100644
--- a/sc2/src/sc2code/libs/graphics/sdl/dcqueue.c
+++ b/sc2/src/sc2code/libs/graphics/sdl/dcqueue.c
@@ -44,7 +44,11 @@ _lock (void)
 	Uint32 current_thread = SDL_ThreadID ();
 	if (DCQ_locking_thread != current_thread)
 	{
-		LockMutex (DCQ_lock);
+		if (LockMutex (DCQ_lock))
+		{
+			fprintf (stderr, "DCQ lock attempt failed!\n");
+			return;
+		}
 		DCQ_locking_thread = current_thread;
 	}
 	++DCQ_locking_depth;
diff --git a/sc2/src/sc2code/libs/threadlib.h b/sc2/src/sc2code/libs/threadlib.h
index 89347bb66..9ca91a644 100644
--- a/sc2/src/sc2code/libs/threadlib.h
+++ b/sc2/src/sc2code/libs/threadlib.h
@@ -67,10 +67,10 @@ This is now a compile-time define
 #	endif
 #endif
 
-extern void InitThreadSystem (void);
-extern void UnInitThreadSystem (void);
-extern void init_cond_bank (void);
-extern void uninit_cond_bank (void);
+void InitThreadSystem (void);
+void UnInitThreadSystem (void);
+void init_cond_bank (void);
+void uninit_cond_bank (void);
 
 typedef int (*ThreadFunction) (void *);
 
@@ -88,64 +88,70 @@ typedef struct Thread {
 } *Thread;
 
 #ifdef THREAD_NAMES
-extern Thread CreateThreadAux (ThreadFunction func, void *data,
+Thread CreateThreadAux (ThreadFunction func, void *data,
 		SDWORD stackSize, const char *name);
 #	define CreateThread(func, data, stackSize, name) \
 		CreateThreadAux ((func), (data), (stackSize), (name))
 #else  /* !defined(THREAD_NAMES) */
-extern Thread CreateThreadAux (ThreadFunction func, void *data,
+Thread CreateThreadAux (ThreadFunction func, void *data,
 		SDWORD stackSize);
 #	define CreateThread(func, data, stackSize, name) \
 		CreateThreadAux ((func), (data), (stackSize))
 #endif  /* !defined(THREAD_NAMES) */
-extern void SleepThread (TimePeriod timePeriod);
-extern void SleepThreadUntil (TimeCount wakeTime);
-extern void TaskSwitch (void);
-extern void WaitThread (Thread thread, int *status);
+void SleepThread (TimePeriod timePeriod);
+void SleepThreadUntil (TimeCount wakeTime);
+void TaskSwitch (void);
+void WaitThread (Thread thread, int *status);
 
 typedef void *Semaphore;
 #ifdef DEBUG_TRACK_SEM
-extern Semaphore CreateSemaphoreAux (DWORD initial, const char *sem_name);
+Semaphore CreateSemaphoreAux (DWORD initial, const char *sem_name);
 #	define CreateSemaphore(initial,sem_name) \
 		CreateSemaphoreAux ((initial), (sem_name))
-extern void ResetSemaphoreOwnerAux (Semaphore sem);
+void ResetSemaphoreOwnerAux (Semaphore sem);
 #	define ResetSemaphoreOwner(sem_name) \
 		ResetSemaphoreOwnerAux (sem_name)
 #else
-extern Semaphore CreateSemaphoreAux (DWORD initial);
+Semaphore CreateSemaphoreAux (DWORD initial);
 #	define CreateSemaphore(initial,sem_name) \
 		CreateSemaphoreAux ((initial))
 #	define ResetSemaphoreOwner(sem_name)
 #endif
-extern DWORD SemaphoreValue (Semaphore sem);
-extern void DestroySemaphore (Semaphore sem);
-extern int SetSemaphore (Semaphore sem);
-extern int TrySetSemaphore (Semaphore sem);
-extern int TimeoutSetSemaphore (Semaphore sem, TimePeriod timeout);
-extern void ClearSemaphore (Semaphore sem);
+DWORD SemaphoreValue (Semaphore sem);
+void DestroySemaphore (Semaphore sem);
+int SetSemaphore (Semaphore sem);
+int TrySetSemaphore (Semaphore sem);
+int TimeoutSetSemaphore (Semaphore sem, TimePeriod timeout);
+void ClearSemaphore (Semaphore sem);
 #ifdef PROFILE_THREADS
-extern void PrintThreadsStats (void);
+void PrintThreadsStats (void);
 #endif  /* PROFILE_THREADS */
 
 typedef void *Mutex;
-extern Mutex CreateMutex (void);
-extern void DestroyMutex (Mutex sem);
-extern int LockMutex (Mutex sem);
-extern void UnlockMutex (Mutex sem);
+Mutex CreateMutex (void);
+void DestroyMutex (Mutex sem);
+int LockMutex (Mutex sem);
+void UnlockMutex (Mutex sem);
+
+typedef void *CrossThreadMutex;
+CrossThreadMutex CreateCrossThreadMutex (const char *name);
+void DestroyCrossThreadMutex (CrossThreadMutex ctm);
+int LockCrossThreadMutex (CrossThreadMutex ctm);
+void UnlockCrossThreadMutex (CrossThreadMutex ctm);
 
 typedef void *CondVar;
-extern CondVar CreateCondVar (void);
-extern void DestroyCondVar (CondVar);
-extern void WaitCondVar (CondVar);
-extern void WaitProtectedCondVar (CondVar, Mutex);
-extern void SignalCondVar (CondVar);
-extern void BroadcastCondVar (CondVar);
+CondVar CreateCondVar (void);
+void DestroyCondVar (CondVar);
+void WaitCondVar (CondVar);
+void WaitProtectedCondVar (CondVar, Mutex);
+void SignalCondVar (CondVar);
+void BroadcastCondVar (CondVar);
 
-extern DWORD CurrentThreadID (void);
+DWORD CurrentThreadID (void);
 
-extern int  FindSignalChannel ();
-extern void WaitForSignal (int);
-extern void SignalThread (DWORD);
+int  FindSignalChannel ();
+void WaitForSignal (int);
+void SignalThread (DWORD);
 
 #endif  /* _THREADLIB_H */
 
diff --git a/sc2/src/sc2code/libs/threads/sdl/sdlthreads.c b/sc2/src/sc2code/libs/threads/sdl/sdlthreads.c
index ddf67fc6e..3fbd2c31b 100644
--- a/sc2/src/sc2code/libs/threads/sdl/sdlthreads.c
+++ b/sc2/src/sc2code/libs/threads/sdl/sdlthreads.c
@@ -17,6 +17,8 @@
 /* By Serge van den Boom
  */
 
+#include <stdlib.h>
+#include "misc.h"
 #include "sdlthreads.h"
 
 #if defined(PROFILE_THREADS) && !defined(WIN32)
@@ -84,3 +86,76 @@ SDLWrapper_WaitCondVar (CondVar cv) {
 		fprintf (stderr, "Error result from SDL_CondWait: %d\n", result);
 	}
 }
+
+/* Code for cross-thread mutexes.  The prototypes for these functions are in threadlib.h. */
+
+typedef struct _ctm {
+	SDL_mutex *mutex;
+	SDL_cond  *cond;
+	const char *name;
+	BOOLEAN   locked;
+} _NativeCTM;
+
+CrossThreadMutex
+CreateCrossThreadMutex (const char *name)
+{
+	_NativeCTM *result = HMalloc (sizeof (_NativeCTM));
+	result->mutex  = SDL_CreateMutex ();
+	result->cond   = SDL_CreateCond ();
+	result->name   = name;
+	result->locked = FALSE;
+	return (CrossThreadMutex)result;
+}
+
+void
+DestroyCrossThreadMutex (CrossThreadMutex val)
+{
+	_NativeCTM *ctm = (_NativeCTM *)val;
+	if (ctm)
+	{
+		SDL_DestroyMutex (ctm->mutex);
+		SDL_DestroyCond (ctm->cond);
+		HFree (ctm);
+	}
+}
+
+int
+LockCrossThreadMutex (CrossThreadMutex val)
+{
+	_NativeCTM *ctm = (_NativeCTM *)val;
+	if (SDL_mutexP (ctm->mutex))
+	{
+		fprintf (stderr, "LockCrossThreadMutex failed to lock internal mutex in %s!\n", ctm->name);
+		return -1;
+	}
+	while (ctm->locked)
+	{
+		// fprintf (stderr, "Thread %8x goes to sleep, waiting on %s\n", SDL_ThreadID (), ctm->name);
+		SDL_CondWait (ctm->cond, ctm->mutex);
+		// fprintf (stderr, "Thread %8x awakens.\n", SDL_ThreadID ());
+	}
+	ctm->locked = TRUE;
+	SDL_mutexV (ctm->mutex);
+	return 0; /* success */
+}
+
+void
+UnlockCrossThreadMutex (CrossThreadMutex val)
+{
+	_NativeCTM *ctm = (_NativeCTM *)val;
+	if (SDL_mutexP (ctm->mutex))
+	{
+		fprintf (stderr, "UnlockCrossThreadMutex failed to lock internal mutex in %s!\n", ctm->name);
+		return;
+	}
+	if (ctm->locked)
+	{
+		ctm->locked = FALSE;
+		SDL_CondSignal (ctm->cond);
+	}
+	else
+	{
+		fprintf (stderr, "Double unlock attempt on %s ignored.\n", ctm->name);
+	}
+	SDL_mutexV (ctm->mutex);
+}
diff --git a/sc2/src/sc2code/load.c b/sc2/src/sc2code/load.c
index 7af4b0e86..49a2221cb 100644
--- a/sc2/src/sc2code/load.c
+++ b/sc2/src/sc2code/load.c
@@ -96,7 +96,7 @@ LoadGame (COUNT which_game, SUMMARY_DESC *summary_desc)
 		uio_Stream *fp;
 		DECODE_REF fh;
 		COUNT num_links;
-		Semaphore clock_sem;
+		CrossThreadMutex clock_lock;
 		Task clock_task;
 		QUEUE event_q, encounter_q, avail_q, npc_q, player_q;
 		STAR_DESC SD;
@@ -126,7 +126,7 @@ LoadGame (COUNT which_game, SUMMARY_DESC *summary_desc)
 		ReinitQueue (&GLOBAL (npc_built_ship_q));
 		ReinitQueue (&GLOBAL (built_ship_q));
 
-		clock_sem = GLOBAL (GameClock.clock_sem);
+		clock_lock = GLOBAL (GameClock.clock_lock);
 		clock_task = GLOBAL (GameClock.clock_task);
 		event_q = GLOBAL (GameClock.event_q);
 		encounter_q = GLOBAL (encounter_q);
@@ -141,7 +141,7 @@ LoadGame (COUNT which_game, SUMMARY_DESC *summary_desc)
 		NextActivity = GLOBAL (CurrentActivity);
 		GLOBAL (CurrentActivity) = Activity;
 
-		GLOBAL (GameClock.clock_sem) = clock_sem;
+		GLOBAL (GameClock.clock_lock) = clock_lock;
 		GLOBAL (GameClock.clock_task) = clock_task;
 		GLOBAL (GameClock.event_q) = event_q;
 		GLOBAL (encounter_q) = encounter_q;
diff --git a/sc2/src/sc2code/melee.c b/sc2/src/sc2code/melee.c
index 20a2bceb0..ac55265b7 100644
--- a/sc2/src/sc2code/melee.c
+++ b/sc2/src/sc2code/melee.c
@@ -224,9 +224,9 @@ DrawPickFrame (PMELEE_STATE pMS)
 				+ (ship_r.extent.height - r.extent.height));
 	SetFrameHot (F, MAKE_HOT_SPOT (r.corner.x, r.corner.y));
 	DrawMeleeIcon (27);
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 	DrawMeleeShipStrings (pMS, (BYTE)pMS->CurIndex);
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 }
 
 static void
@@ -518,19 +518,19 @@ int flash_selection_func(void* data)
 #define FLASH_RATE (ONE_SECOND / 8)
 		CONTEXT OldContext;
 
-		SetSemaphore (GraphicsSem);
+		LockCrossThreadMutex (GraphicsLock);
 		OldContext = SetContext (SpaceContext);
 		Deselect (pMeleeState->MeleeOption);
 		SetContext (OldContext);
-		ClearSemaphore (GraphicsSem);
+		UnlockCrossThreadMutex (GraphicsLock);
 		SleepThreadUntil (TimeIn + FLASH_RATE);
 		TimeIn = GetTimeCounter ();
 
-		SetSemaphore (GraphicsSem);
+		LockCrossThreadMutex (GraphicsLock);
 		OldContext = SetContext (SpaceContext);
 		Select (pMeleeState->MeleeOption);
 		SetContext (OldContext);
-		ClearSemaphore (GraphicsSem);
+		UnlockCrossThreadMutex (GraphicsLock);
 		SleepThreadUntil (TimeIn + FLASH_RATE);
 		TimeIn = GetTimeCounter ();
 	}
@@ -571,7 +571,7 @@ DrawMeleeShipStrings (PMELEE_STATE pMS, BYTE NewStarShip)
 	STARSHIPPTR StarShipPtr;
 	CONTEXT OldContext;
 
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 
 	OldContext = SetContext (StatusContext);
 	GetContextClipRect (&OldRect);
@@ -630,7 +630,7 @@ DrawMeleeShipStrings (PMELEE_STATE pMS, BYTE NewStarShip)
 	SetContextClipRect (&OldRect);
 	SetContext (OldContext);
 
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 }
 
 static COUNT
@@ -846,7 +846,7 @@ DoLoadTeam (PMELEE_STATE pMS)
 
 	if (!pMS->Initialized)
 	{
-		SetSemaphore (GraphicsSem);
+		LockCrossThreadMutex (GraphicsLock);
 		Select (pMS->MeleeOption);
 		if ((pMS->TopTeamIndex = pMS->CurIndex) == (COUNT)~0)
 			pMS->TopTeamIndex = pMS->CurIndex = 0;
@@ -858,7 +858,7 @@ DoLoadTeam (PMELEE_STATE pMS)
 		DrawFileStrings (pMS, -1);
 		pMS->Initialized = TRUE;
 		pMS->InputFunc = DoLoadTeam;
-		ClearSemaphore (GraphicsSem);
+		UnlockCrossThreadMutex (GraphicsLock);
 	}
 	else if (CurrentMenuState.select | CurrentMenuState.cancel)
 	{
@@ -876,9 +876,9 @@ DoLoadTeam (PMELEE_STATE pMS)
 			RECT r;
 			
 			GetFrameRect (SetAbsFrameIndex (MeleeFrame, 28), &r);
-			SetSemaphore (GraphicsSem);
+			LockCrossThreadMutex (GraphicsLock);
 			RepairMeleeFrame (&r);
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 		}
 		InTime = GetTimeCounter ();
 	}
@@ -932,7 +932,7 @@ DoLoadTeam (PMELEE_STATE pMS)
 
 		if (index != old_index)
 		{
-			SetSemaphore (GraphicsSem);
+			LockCrossThreadMutex (GraphicsLock);
 			if ((int)NewTop == (int)pMS->TopTeamIndex)
 				Deselect (pMS->MeleeOption);
 			else
@@ -941,7 +941,7 @@ DoLoadTeam (PMELEE_STATE pMS)
 				DrawFileStrings (pMS, -1);
 			}
 			pMS->CurIndex = index;
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 		}
 	}
 
@@ -1076,7 +1076,7 @@ DoSaveTeam (PMELEE_STATE pMS)
 
 	sprintf (file, "%s.mle", pMS->TeamImage[pMS->side].TeamName);
 
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 	OldContext = SetContext (ScreenContext);
 	ConfirmSaveLoad (&MsgStamp);
 	save_fp = res_OpenResFile (meleeDir, file, "wb");
@@ -1097,7 +1097,7 @@ DoSaveTeam (PMELEE_STATE pMS)
 		DrawStamp (&MsgStamp);
 		DestroyDrawable (ReleaseDrawable (MsgStamp.frame));
 		SetContext (OldContext);
-		ClearSemaphore (GraphicsSem);
+		UnlockCrossThreadMutex (GraphicsLock);
 
 		DeleteResFile (meleeDir, file);
 		SaveProblem ();
@@ -1110,7 +1110,7 @@ DoSaveTeam (PMELEE_STATE pMS)
 		DrawStamp (&MsgStamp);
 		DestroyDrawable (ReleaseDrawable (MsgStamp.frame));
 		SetContext (OldContext);
-		ClearSemaphore (GraphicsSem);
+		UnlockCrossThreadMutex (GraphicsLock);
 	}
 	
 	return (save_fp != 0);
@@ -1135,12 +1135,12 @@ DeleteCurrentShip (PMELEE_STATE pMS)
 	
 		pMS->TeamImage[pMS->side].ShipList[pMS->row][pMS->col] = (BYTE)~0;
        	}
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 	GetShipBox (&r, pMS->side, pMS->row, pMS->col);
 	RepairMeleeFrame (&r);
 
 	DrawTeamString (pMS, 4);
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 
 }
 
@@ -1177,12 +1177,12 @@ DoEdit (PMELEE_STATE pMS)
 			|| (CurrentMenuState.right
 			&& (pMS->col == NUM_MELEE_COLUMNS - 1 || pMS->row == NUM_MELEE_ROWS))))
 	{
-		SetSemaphore (GraphicsSem);
+		LockCrossThreadMutex (GraphicsLock);
 		Deselect (EDIT_MELEE);
 		pMS->CurIndex = (COUNT)~0;
 		pMS->MeleeOption = START_MELEE;
 		pMS->InputFunc = DoMelee;
-		ClearSemaphore (GraphicsSem);
+		UnlockCrossThreadMutex (GraphicsLock);
 		InTime = GetTimeCounter ();
 	}
 	else if (pMS->row < NUM_MELEE_ROWS
@@ -1213,7 +1213,7 @@ DoEdit (PMELEE_STATE pMS)
 			if (pMS->CurIndex != (BYTE)~0)
 			{
 				UNICODE ch;
-				SetSemaphore (GraphicsSem);
+				LockCrossThreadMutex (GraphicsLock);
 				if (pMS->Initialized == 1)
 				{
 					FlushInput ();
@@ -1226,15 +1226,15 @@ DoEdit (PMELEE_STATE pMS)
 					pMS->Initialized = 1;
 					DisableCharacterMode ();
 				}
-				ClearSemaphore (GraphicsSem);
+				UnlockCrossThreadMutex (GraphicsLock);
 				return (TRUE);
 			}
 			else if (CurrentMenuState.select)
 			{
 				pMS->CurIndex = 0;
-				SetSemaphore (GraphicsSem);
+				LockCrossThreadMutex (GraphicsLock);
 				DrawTeamString (pMS, 1);
-				ClearSemaphore (GraphicsSem);
+				UnlockCrossThreadMutex (GraphicsLock);
 				EnableCharacterMode ();
 				return (TRUE);
 			}
@@ -1282,7 +1282,7 @@ DoEdit (PMELEE_STATE pMS)
 
 		if (col != pMS->col || row != pMS->row || side != pMS->side)
 		{
-			SetSemaphore (GraphicsSem);
+			LockCrossThreadMutex (GraphicsLock);
 			Deselect (EDIT_MELEE);
 			pMS->side = side;
 			pMS->row = row;
@@ -1291,7 +1291,7 @@ DoEdit (PMELEE_STATE pMS)
 				pMS->CurIndex = (BYTE)~0;
 			else
 				pMS->CurIndex = pMS->TeamImage[side].ShipList[row][col];
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 
 			DrawMeleeShipStrings (pMS, (BYTE)(pMS->CurIndex));
 		}
@@ -1319,21 +1319,21 @@ DoPickShip (PMELEE_STATE pMS)
 
 		if (pMS->Initialized == 0)
 		{
-			SetSemaphore (GraphicsSem);
+			LockCrossThreadMutex (GraphicsLock);
 			Deselect (EDIT_MELEE);
 			pMS->InputFunc = DoPickShip;
 			DrawPickFrame (pMS);
 			pMS->Initialized = TRUE;
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 		}
 		else
 		{
-			SetSemaphore (GraphicsSem);
+			LockCrossThreadMutex (GraphicsLock);
 			Deselect (EDIT_MELEE);
 			pMS->Initialized = TRUE;
 			AdvanceCursor (pMS);
 			pMS->CurIndex = pMS->TeamImage[pMS->side].ShipList[pMS->row][pMS->col];
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 
 			DrawMeleeShipStrings (pMS, (BYTE)(pMS->CurIndex));
 		}
@@ -1353,10 +1353,10 @@ DoPickShip (PMELEE_STATE pMS)
 			UnlockStarShip (&master_q, hStarShip);
 
 			pMS->TeamImage[pMS->side].ShipList[pMS->row][pMS->col] = pMS->CurIndex;
-			SetSemaphore (GraphicsSem);
+			LockCrossThreadMutex (GraphicsLock);
 			DrawTeamString (pMS, 4);
 			DrawShipBox (pMS, FALSE);
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 			AdvanceCursor (pMS);
 		}
 
@@ -1364,9 +1364,9 @@ DoPickShip (PMELEE_STATE pMS)
 			RECT r;
 			
 			GetFrameRect (SetAbsFrameIndex (MeleeFrame, 27), &r);
-			SetSemaphore (GraphicsSem);
+			LockCrossThreadMutex (GraphicsLock);
 			RepairMeleeFrame (&r);
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 		}
 
 		pMS->CurIndex = pMS->TeamImage[pMS->side].ShipList[pMS->row][pMS->col];
@@ -1416,10 +1416,10 @@ DoPickShip (PMELEE_STATE pMS)
 
 		if (NewStarShip != pMS->CurIndex)
 		{
-			SetSemaphore (GraphicsSem);
+			LockCrossThreadMutex (GraphicsLock);
 			Deselect (EDIT_MELEE);
 			pMS->CurIndex = NewStarShip;
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 			DrawMeleeShipStrings (pMS, NewStarShip);
 		}
 	}
@@ -1469,9 +1469,9 @@ FreeMeleeInfo (PMELEE_STATE pMS)
 {
 	if (pMS->flash_task)
 	{
-		SetSemaphore (GraphicsSem);
+		LockCrossThreadMutex (GraphicsLock);
 		Task_SetState (pMS->flash_task, TASK_EXIT);
-		ClearSemaphore (GraphicsSem);
+		UnlockCrossThreadMutex (GraphicsLock);
 		pMS->flash_task = 0;
 	}
 	DestroyDirEntryTable (ReleaseDirEntryTable (pMS->TeamDE));
@@ -1591,9 +1591,9 @@ DoMelee (PMELEE_STATE pMS)
 	{
 		pMS->Initialized = TRUE;
 		pMS->MeleeOption = START_MELEE;
-		SetSemaphore (GraphicsSem);
+		LockCrossThreadMutex (GraphicsLock);
 		InitMelee (pMS);
-		ClearSemaphore (GraphicsSem);
+		UnlockCrossThreadMutex (GraphicsLock);
 		{
 			BYTE clut_buf[] = {FadeAllToColor};
 				
@@ -1603,10 +1603,10 @@ DoMelee (PMELEE_STATE pMS)
 	}
 	else if (CurrentMenuState.cancel || CurrentMenuState.left)
 	{
-		SetSemaphore (GraphicsSem);
+		LockCrossThreadMutex (GraphicsLock);
 		InTime = GetTimeCounter ();
 		Deselect (pMS->MeleeOption);
-		ClearSemaphore (GraphicsSem);
+		UnlockCrossThreadMutex (GraphicsLock);
 		pMS->MeleeOption = EDIT_MELEE;
 		pMS->Initialized = FALSE;
 		if (CurrentMenuState.cancel)
@@ -1644,11 +1644,11 @@ DoMelee (PMELEE_STATE pMS)
 
 		if (NewMeleeOption != pMS->MeleeOption)
 		{
-			SetSemaphore (GraphicsSem);
+			LockCrossThreadMutex (GraphicsLock);
 			Deselect (pMS->MeleeOption);
 			pMS->MeleeOption = NewMeleeOption;
 			Select (pMS->MeleeOption);
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 		}
 
 		if (CurrentMenuState.select || force_select)
@@ -1665,9 +1665,9 @@ DoMelee (PMELEE_STATE pMS)
 
 					if (pMS->flash_task)
 					{
-						SetSemaphore (GraphicsSem);
+						LockCrossThreadMutex (GraphicsLock);
 						Task_SetState (pMS->flash_task, TASK_EXIT);
-						ClearSemaphore (GraphicsSem);
+						UnlockCrossThreadMutex (GraphicsLock);
 						pMS->flash_task = 0;
 					}
 					
@@ -1681,9 +1681,9 @@ DoMelee (PMELEE_STATE pMS)
 					}
 					do
 					{
-						SetSemaphore (GraphicsSem);
+						LockCrossThreadMutex (GraphicsLock);
 						BuildAndDrawShipList (pMS);
-						ClearSemaphore (GraphicsSem);
+						UnlockCrossThreadMutex (GraphicsLock);
 
 						WaitForSoundEnd (TFBSOUND_WAIT_ALL);
 
diff --git a/sc2/src/sc2code/menu.c b/sc2/src/sc2code/menu.c
index c041cd204..487768c37 100644
--- a/sc2/src/sc2code/menu.c
+++ b/sc2/src/sc2code/menu.c
@@ -516,7 +516,7 @@ DrawMenuStateStrings (BYTE beg_index, SWORD NewState)
 	if (NewState <= end_index - beg_index)
 		s.frame = SetAbsFrameIndex (PlayFrame, beg_index + NewState);
 
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 	OldContext = SetContext (StatusContext);
 	GetContextClipRect (&r);
 	s.origin.x = RADAR_X - r.corner.x;
@@ -631,6 +631,6 @@ DrawMenuStateStrings (BYTE beg_index, SWORD NewState)
 			&& flash_rect.extent.height == RADAR_HEIGHT)
 		SetFlashRect ((PRECT)~0L, (FRAME)0);
 	SetContext (OldContext);
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 }
 
diff --git a/sc2/src/sc2code/outfit.c b/sc2/src/sc2code/outfit.c
index e58bc0c07..37d29fc88 100644
--- a/sc2/src/sc2code/outfit.c
+++ b/sc2/src/sc2code/outfit.c
@@ -220,7 +220,7 @@ DoInstallModule (PMENU_STATE pMS)
 
 		pMS->InputFunc = DoInstallModule;
 
-		SetSemaphore (GraphicsSem);
+		LockCrossThreadMutex (GraphicsLock);
 
 		SetContext (SpaceContext);
 		ClearSISRect (CLEAR_SIS_RADAR);
@@ -270,7 +270,7 @@ DoInstallModule (PMENU_STATE pMS)
 			}
 		}
 
-		SetSemaphore (GraphicsSem);
+		LockCrossThreadMutex (GraphicsLock);
 		SetContext (SpaceContext);
 
 		SetFlashRect (NULL_PTR, (FRAME)0);
@@ -354,15 +354,15 @@ DoInstallModule (PMENU_STATE pMS)
 		else
 		{
 			SetContext (StatusContext);
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 			DrawMenuStateStrings (PM_FUEL, pMS->CurState = OUTFIT_MODULES);
-			SetSemaphore (GraphicsSem);
+			LockCrossThreadMutex (GraphicsLock);
 			SetFlashRect ((PRECT)~0L, (FRAME)0);
 
 			pMS->InputFunc = DoOutfit;
 			ClearSISRect (DRAW_SIS_DISPLAY);
 		}
-		ClearSemaphore (GraphicsSem);
+		UnlockCrossThreadMutex (GraphicsLock);
 	}
 	else if (motion)
 	{
@@ -408,7 +408,7 @@ DoInstallModule (PMENU_STATE pMS)
 				|| (NewItem >= GUN_WEAPON && NewItem <= CANNON_WEAPON
 				&& pMS->delta_item > 0 && pMS->delta_item < 13)));
 
-		SetSemaphore (GraphicsSem);
+		LockCrossThreadMutex (GraphicsLock);
 		if (NewState < EMPTY_SLOT)
 		{
 			if (NewItem != pMS->CurState)
@@ -505,7 +505,7 @@ InitFlash:
 			else
 				SetFlashRect (&pMS->flash_rect0, (FRAME)0);
 		}
-		ClearSemaphore (GraphicsSem);
+		UnlockCrossThreadMutex (GraphicsLock);
 	}
 
 	return (TRUE);
@@ -519,7 +519,7 @@ ChangeFuelQuantity ()
 	
 	if (CurrentMenuState.up)
 	{
-		SetSemaphore (GraphicsSem);
+		LockCrossThreadMutex (GraphicsLock);
 		SetContext (SpaceContext);
 		if (GetFTankCapacity (&r.corner) > GLOBAL_SIS (FuelOnBoard)
 			&& GLOBAL_SIS (ResUnits) >=
@@ -541,11 +541,11 @@ ChangeFuelQuantity ()
 			GetGaugeRect (&r, FALSE);
 			SetFlashRect (&r, (FRAME)0);
 		}
-		ClearSemaphore (GraphicsSem);
+		UnlockCrossThreadMutex (GraphicsLock);
 	}
 	else if (CurrentMenuState.down)
 	{
-		SetSemaphore (GraphicsSem);
+		LockCrossThreadMutex (GraphicsLock);
 		SetContext (SpaceContext);
 		if (GLOBAL_SIS (FuelOnBoard))
 		{
@@ -563,7 +563,7 @@ ChangeFuelQuantity ()
 		SetContext (StatusContext);
 		GetGaugeRect (&r, FALSE);
 		SetFlashRect (&r, (FRAME)0);
-		ClearSemaphore (GraphicsSem);
+		UnlockCrossThreadMutex (GraphicsLock);
 	}
 }
 
@@ -600,7 +600,7 @@ DoOutfit (PMENU_STATE pMS)
 			SetTransitionSource (NULL);
 			BatchGraphics ();
 			DrawSISFrame ();
-			SetSemaphore (GraphicsSem);
+			LockCrossThreadMutex (GraphicsLock);
 			DrawSISMessage (GAME_STRING (STARBASE_STRING_BASE + 2));
 			DrawSISTitle (GAME_STRING (STARBASE_STRING_BASE));
 
@@ -656,13 +656,13 @@ DoOutfit (PMENU_STATE pMS)
 					DrawStamp ((PSTAMP)&s);
 			}
 
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 			DrawMenuStateStrings (PM_FUEL, pMS->CurState);
-			SetSemaphore (GraphicsSem);
+			LockCrossThreadMutex (GraphicsLock);
 			DrawFlagshipName (FALSE);
 			if (optWhichFonts == OPT_PC)
 				DrawFlagshipStats ();
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 
 			{
 				RECT r;
@@ -676,9 +676,9 @@ DoOutfit (PMENU_STATE pMS)
 			PlayMusic (pMS->hMusic, TRUE, 1);
 			UnbatchGraphics ();
 			
-			SetSemaphore (GraphicsSem);
+			LockCrossThreadMutex (GraphicsLock);
 			SetFlashRect ((PRECT)~0L, (FRAME)0);
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 
 			GLOBAL_SIS (FuelOnBoard) =
 					(GLOBAL_SIS (FuelOnBoard)
@@ -695,9 +695,9 @@ DoOutfit (PMENU_STATE pMS)
 		if (pMS->CurState == OUTFIT_DOFUEL)
 		{
 			pMS->CurState = OUTFIT_FUEL;
-			SetSemaphore (GraphicsSem);
+			LockCrossThreadMutex (GraphicsLock);
 			SetFlashRect ((PRECT)~0L, (FRAME)0);
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 		}
 		else
 		{
@@ -719,18 +719,18 @@ ExitOutfit:
 				RECT r;
 
 				pMS->CurState = OUTFIT_DOFUEL;
-				SetSemaphore (GraphicsSem);
+				LockCrossThreadMutex (GraphicsLock);
 				SetContext (StatusContext);
 				GetGaugeRect (&r, FALSE);
 				SetFlashRect (&r, (FRAME)0);
-				ClearSemaphore (GraphicsSem);
+				UnlockCrossThreadMutex (GraphicsLock);
 				break;
 			}
 			case OUTFIT_DOFUEL:
 				pMS->CurState = OUTFIT_FUEL;
-				SetSemaphore (GraphicsSem);
+				LockCrossThreadMutex (GraphicsLock);
 				SetFlashRect ((PRECT)~0L, (FRAME)0);
-				ClearSemaphore (GraphicsSem);
+				UnlockCrossThreadMutex (GraphicsLock);
 				break;
 			case OUTFIT_MODULES:
 				pMS->CurState = EMPTY_SLOT + 2;
@@ -746,9 +746,9 @@ ExitOutfit:
 				if (GameOptions () == 0)
 					goto ExitOutfit;
 				DrawMenuStateStrings (PM_FUEL, pMS->CurState);
-				SetSemaphore (GraphicsSem);
+				LockCrossThreadMutex (GraphicsLock);
 				SetFlashRect ((PRECT)~0L, (FRAME)0);
-				ClearSemaphore (GraphicsSem);
+				UnlockCrossThreadMutex (GraphicsLock);
 				break;
 		}
 	}
diff --git a/sc2/src/sc2code/pickmele.c b/sc2/src/sc2code/pickmele.c
index 326e85023..845078c9d 100644
--- a/sc2/src/sc2code/pickmele.c
+++ b/sc2/src/sc2code/pickmele.c
@@ -119,7 +119,7 @@ GetMeleeStarShip (STARSHIPPTR LastStarShipPtr, COUNT which_player)
 
 		TimeOut = GetTimeCounter () + (ONE_SECOND * 4);
 		SetContext (OldContext);
-		ClearSemaphore (GraphicsSem);
+		UnlockCrossThreadMutex (GraphicsLock);
 
 		UpdateInputState ();
 		PressState = AnyButtonPress (TRUE);
@@ -142,7 +142,7 @@ GetMeleeStarShip (STARSHIPPTR LastStarShipPtr, COUNT which_player)
 			ConfirmExit ();
 		*/
 
-		SetSemaphore (GraphicsSem);
+		LockCrossThreadMutex (GraphicsLock);
 
 		return (0);
 	}
@@ -243,7 +243,7 @@ GetMeleeStarShip (STARSHIPPTR LastStarShipPtr, COUNT which_player)
 				col = new_col;
 
 				PlaySoundEffect (MenuSounds, 0, NotPositional (), NULL, 0);
-				SetSemaphore (GraphicsSem);
+				LockCrossThreadMutex (GraphicsLock);
 ChangeSelection:
 				flash_rect.corner.x = PICK_X_OFFS
 						+ ((ICON_WIDTH + 2) * col);
@@ -293,12 +293,12 @@ ChangeSelection:
 						UnlockStarShip (&race_q[which_player], hBattleShip);
 					}
 				}
-				ClearSemaphore (GraphicsSem);
+				UnlockCrossThreadMutex (GraphicsLock);
 			}
 		}
 	}
 
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 	SetFlashRect (NULL_PTR, (FRAME)0);
 	
 	if (hBattleShip == 0)
diff --git a/sc2/src/sc2code/pickship.c b/sc2/src/sc2code/pickship.c
index ecc009baa..eb3b46b65 100644
--- a/sc2/src/sc2code/pickship.c
+++ b/sc2/src/sc2code/pickship.c
@@ -44,7 +44,7 @@ DoPickBattleShip (PMENU_STATE pMS)
 		pMS->Initialized = TRUE;
 		pMS->InputFunc = DoPickBattleShip;
 
-		SetSemaphore (GraphicsSem);
+		LockCrossThreadMutex (GraphicsLock);
 
 		goto ChangeSelection;
 	}
@@ -84,7 +84,7 @@ DoPickBattleShip (PMENU_STATE pMS)
 			else if (new_row == NUM_PICK_SHIP_ROWS)
 				new_row = 0;
 
-			SetSemaphore (GraphicsSem);
+			LockCrossThreadMutex (GraphicsLock);
 
 #ifdef NEVER
 			SetContextForeGroundColor (BUILD_COLOR (MAKE_RGB15 (0xA, 0xA, 0xA), 0x1D));
@@ -211,7 +211,7 @@ ChangeSelection:
 
 			SetFlashRect ((RECT *)0, (FRAME)0);
 			SetFlashRect (&pMS->flash_rect0, (FRAME)0);
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 		}
 	}
 
@@ -247,11 +247,11 @@ OldContext = SetContext (SpaceContext);
 		MenuState.flash_rect1.corner = pick_r.corner;
 		MenuState.flash_rect1.extent.width = 0;
 
-		ClearSemaphore (GraphicsSem);
+		UnlockCrossThreadMutex (GraphicsLock);
 		pMenuState = &MenuState;
 		DoInput ((PVOID)&MenuState, TRUE);
 		pMenuState = 0;
-		SetSemaphore (GraphicsSem);
+		LockCrossThreadMutex (GraphicsLock);
 
 		SetFlashRect (NULL_PTR, (FRAME)0);
 
diff --git a/sc2/src/sc2code/planets/cargo.c b/sc2/src/sc2code/planets/cargo.c
index b67c55bf8..bf2d1bcf0 100644
--- a/sc2/src/sc2code/planets/cargo.c
+++ b/sc2/src/sc2code/planets/cargo.c
@@ -69,7 +69,7 @@ DrawCargoStrings (BYTE OldElement, BYTE NewElement)
 	CONTEXT OldContext;
 	UNICODE rt_amount_buf[10];
 
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 
 	OldContext = SetContext (StatusContext);
 	SetContextFont (TinyFont);
@@ -272,7 +272,7 @@ DrawCargoStrings (BYTE OldElement, BYTE NewElement)
 
 	UnbatchGraphics ();
 	SetContext (OldContext);
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 }
 
 static BOOLEAN
@@ -299,9 +299,9 @@ DoDiscardCargo (PMENU_STATE pMS)
 	}
 	else if (cancel)
 	{
-		SetSemaphore (GraphicsSem);
+		LockCrossThreadMutex (GraphicsLock);
 		ClearSISRect (DRAW_SIS_DISPLAY);
-		ClearSemaphore (GraphicsSem);
+		UnlockCrossThreadMutex (GraphicsLock);
 
 		return (FALSE);
 	}
@@ -312,10 +312,10 @@ DoDiscardCargo (PMENU_STATE pMS)
 			--GLOBAL_SIS (ElementAmounts[pMS->CurState - 1]);
 			DrawCargoStrings ((BYTE)(pMS->CurState - 1), (BYTE)(pMS->CurState - 1));
 
-			SetSemaphore (GraphicsSem);
+			LockCrossThreadMutex (GraphicsLock);
 			--GLOBAL_SIS (TotalElementMass);
 			ShowRemainingCapacity ();
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 		}
 	}
 	else
@@ -336,9 +336,9 @@ DoDiscardCargo (PMENU_STATE pMS)
 		{
 SelectCargo:
 			DrawCargoStrings ((BYTE)(pMS->CurState - 1), (BYTE)(NewState - 1));
-			SetSemaphore (GraphicsSem);
+			LockCrossThreadMutex (GraphicsLock);
 			DrawStatusMessage (GAME_STRING (NewState - 1 + (CARGO_STRING_BASE + 2)));
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 
 			pMS->CurState = NewState;
 		}
@@ -354,9 +354,9 @@ Cargo (PMENU_STATE pMS)
 	--pMS->Initialized;
 	pMS->CurState = 1;
 
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 	DrawStatusMessage ((UNICODE *)~0);
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 
 	DoInput ((PVOID)pMS, TRUE);
 
diff --git a/sc2/src/sc2code/planets/devices.c b/sc2/src/sc2code/planets/devices.c
index 11a94c2dc..5f4110395 100644
--- a/sc2/src/sc2code/planets/devices.c
+++ b/sc2/src/sc2code/planets/devices.c
@@ -40,7 +40,7 @@ DrawDevices (PMENU_STATE pMS, BYTE OldDevice, BYTE NewDevice)
 	RECT r;
 	PBYTE pDeviceMap;
 
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 
 	SetContext (StatusContext);
 	SetContextFont (TinyFont);
@@ -174,7 +174,7 @@ DrawDevices (PMENU_STATE pMS, BYTE OldDevice, BYTE NewDevice)
 		font_DrawText (&t);
 	}
 
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 }
 
 static UWORD
@@ -450,7 +450,7 @@ DoManipulateDevices (PMENU_STATE pMS)
 	{
 		UWORD status;
 
-		SetSemaphore (GraphicsSem);
+		LockCrossThreadMutex (GraphicsLock);
 		status = DeviceFailed (
 				((PBYTE)pMS->CurFrame)[pMS->CurState - 1]
 				);
@@ -461,7 +461,7 @@ DoManipulateDevices (PMENU_STATE pMS)
 		else if (HIBYTE (status) == 0)
 			PlaySoundEffect (SetAbsSoundIndex (MenuSounds, 3),
 					0, NotPositional (), NULL, GAME_SOUND_PRIORITY);
-		ClearSemaphore (GraphicsSem);
+		UnlockCrossThreadMutex (GraphicsLock);
 
 		return ((BOOLEAN)NewState);
 	}
@@ -634,9 +634,9 @@ Devices (PMENU_STATE pMS)
 		if (GLOBAL_SIS (CrewEnlisted) != (COUNT)~0
 				&& !(GLOBAL (CurrentActivity) & CHECK_ABORT))
 		{
-			SetSemaphore (GraphicsSem);
+			LockCrossThreadMutex (GraphicsLock);
 			ClearSISRect (DRAW_SIS_DISPLAY);
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 
 			if (!GET_GAME_STATE (PORTAL_COUNTER)
 					&& !(GLOBAL (CurrentActivity) & START_ENCOUNTER)
diff --git a/sc2/src/sc2code/planets/genchmmr.c b/sc2/src/sc2code/planets/genchmmr.c
index 33e90d4ad..9134e74b3 100644
--- a/sc2/src/sc2code/planets/genchmmr.c
+++ b/sc2/src/sc2code/planets/genchmmr.c
@@ -95,7 +95,7 @@ GenerateChmmr (BYTE control)
 			{
 				RECT r;
 
-				SetSemaphore (GraphicsSem);
+				LockCrossThreadMutex (GraphicsLock);
 
 				pSolarSysState->SysInfo.PlanetInfo.LanderFont =
 						CaptureFont (
@@ -130,7 +130,7 @@ GenerateChmmr (BYTE control)
 						));
 				pSolarSysState->SysInfo.PlanetInfo.LanderFont = 0;
 
-				ClearSemaphore (GraphicsSem);
+				UnlockCrossThreadMutex (GraphicsLock);
 				break;
 			}
 		default:
diff --git a/sc2/src/sc2code/planets/genmyc.c b/sc2/src/sc2code/planets/genmyc.c
index a7b2454cc..ecaccb4ea 100644
--- a/sc2/src/sc2code/planets/genmyc.c
+++ b/sc2/src/sc2code/planets/genmyc.c
@@ -172,9 +172,9 @@ GenerateMycon (BYTE control)
 								break;
 
 							SET_GAME_STATE (SUN_DEVICE_UNGUARDED, 1);
-							SetSemaphore (GraphicsSem);
+							LockCrossThreadMutex (GraphicsLock);
 							RepairSISBorder ();
-							ClearSemaphore (GraphicsSem);
+							UnlockCrossThreadMutex (GraphicsLock);
 						}
 					}
 				}
diff --git a/sc2/src/sc2code/planets/genorz.c b/sc2/src/sc2code/planets/genorz.c
index 39ebf73de..535e0fe14 100644
--- a/sc2/src/sc2code/planets/genorz.c
+++ b/sc2/src/sc2code/planets/genorz.c
@@ -333,9 +333,9 @@ GenerateOrz (BYTE control)
 						if (OrzSurvivors)
 							break;
 
-						SetSemaphore (GraphicsSem);
+						LockCrossThreadMutex (GraphicsLock);
 						RepairSISBorder ();
-						ClearSemaphore (GraphicsSem);
+						UnlockCrossThreadMutex (GraphicsLock);
 					}
 				}
 
diff --git a/sc2/src/sc2code/planets/genpet.c b/sc2/src/sc2code/planets/genpet.c
index 86a40c1cc..6ff841f07 100644
--- a/sc2/src/sc2code/planets/genpet.c
+++ b/sc2/src/sc2code/planets/genpet.c
@@ -85,7 +85,7 @@ ZapToUrquanEncounter (void)
 		dx = (SIZE)square_root ((long)dx * dx + (long)dy * dy)
 				+ (FUEL_TANK_SCALE >> 1);
 
-		SetSemaphore (GraphicsSem);
+		LockCrossThreadMutex (GraphicsLock);
 		DeltaSISGauges (0, -dx, 0);
 		if (GLOBAL_SIS (FuelOnBoard) < 5 * FUEL_TANK_SCALE)
 		{
@@ -95,7 +95,7 @@ ZapToUrquanEncounter (void)
 		}
 		DrawSISMessage (NULL_PTR);
 		DrawHyperCoords (EncounterPtr->SD.star_pt);
-		ClearSemaphore (GraphicsSem);
+		UnlockCrossThreadMutex (GraphicsLock);
 
 		UnlockEncounter (hEncounter);
 	}
diff --git a/sc2/src/sc2code/planets/genthrad.c b/sc2/src/sc2code/planets/genthrad.c
index ee4849441..98b604708 100644
--- a/sc2/src/sc2code/planets/genthrad.c
+++ b/sc2/src/sc2code/planets/genthrad.c
@@ -166,9 +166,9 @@ GenerateThradd (BYTE control)
 							|| (!GET_GAME_STATE (HELIX_UNPROTECTED)
 							&& (BYTE)(GET_GAME_STATE (THRADD_MISSION) - 1) >= 3))
 						break;
-					SetSemaphore (GraphicsSem);
+					LockCrossThreadMutex (GraphicsLock);
 					RepairSISBorder ();
-					ClearSemaphore (GraphicsSem);
+					UnlockCrossThreadMutex (GraphicsLock);
 				}
 
 				if (CurStarDescPtr->Index == AQUA_HELIX_DEFINED
diff --git a/sc2/src/sc2code/planets/genutw.c b/sc2/src/sc2code/planets/genutw.c
index fd313396d..4fddb2efb 100644
--- a/sc2/src/sc2code/planets/genutw.c
+++ b/sc2/src/sc2code/planets/genutw.c
@@ -200,9 +200,9 @@ GenerateUtwig (BYTE control)
 						if (DruugeSurvivors)
 							break;
 
-						SetSemaphore (GraphicsSem);
+						LockCrossThreadMutex (GraphicsLock);
 						RepairSISBorder ();
-						ClearSemaphore (GraphicsSem);
+						UnlockCrossThreadMutex (GraphicsLock);
 						SET_GAME_STATE (BOMB_UNPROTECTED, 1);
 					}
 				}
diff --git a/sc2/src/sc2code/planets/genvux.c b/sc2/src/sc2code/planets/genvux.c
index 46d5a2397..734fb70d5 100644
--- a/sc2/src/sc2code/planets/genvux.c
+++ b/sc2/src/sc2code/planets/genvux.c
@@ -180,9 +180,9 @@ GenerateVUX (BYTE control)
 							|| !GET_GAME_STATE (ZEX_IS_DEAD))
 						break;
 
-					SetSemaphore (GraphicsSem);
+					LockCrossThreadMutex (GraphicsLock);
 					RepairSISBorder ();
-					ClearSemaphore (GraphicsSem);
+					UnlockCrossThreadMutex (GraphicsLock);
 				}
 			}
 
diff --git a/sc2/src/sc2code/planets/lander.c b/sc2/src/sc2code/planets/lander.c
index 868417c92..3c12c15c8 100644
--- a/sc2/src/sc2code/planets/lander.c
+++ b/sc2/src/sc2code/planets/lander.c
@@ -1215,7 +1215,7 @@ ScrollPlanetSide (SIZE dx, SIZE dy, SIZE CountDown)
 		pSolarSysState->MenuState.flash_rect1.corner.y = HIWORD (TimeIn);
 	}
 
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 	OldContext = SetContext (SpaceContext);
 
 	BatchGraphics ();
@@ -1329,7 +1329,7 @@ ScrollPlanetSide (SIZE dx, SIZE dy, SIZE CountDown)
 	UnbatchGraphics ();
 
 	SetContext (OldContext);
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 }
 
 static void
@@ -1353,7 +1353,7 @@ AnimateLaunch (FRAME farray, BOOLEAN ShowPlanetSide)
 		RepairBackRect (&r);
 		DrawStamp (&s);
 
-		ClearSemaphore (GraphicsSem);
+		UnlockCrossThreadMutex (GraphicsLock);
 
 #if 0
 		if (ShowPlanetSide)
@@ -1370,7 +1370,7 @@ AnimateLaunch (FRAME farray, BOOLEAN ShowPlanetSide)
 		SleepThreadUntil (Time + (ONE_SECOND / 22));
 		Time = GetTimeCounter ();
 
-		SetSemaphore (GraphicsSem);
+		LockCrossThreadMutex (GraphicsLock);
 	} while (--num_frames);
 
 	GetFrameRect (s.frame, &r);
@@ -1386,9 +1386,9 @@ InitPlanetSide (void)
 	CONTEXT OldContext;
 	DWORD Time;
 
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 	OldContext = SetContext (RadarContext);
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 
 	Time = GetTimeCounter ();
 
@@ -1397,9 +1397,9 @@ InitPlanetSide (void)
 	s.frame = SetAbsFrameIndex (LanderFrame[0],
 			(ANGLE_TO_FACING (FULL_CIRCLE) << 1) + 1);
 
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 	DrawStamp (&s);
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 
 	SleepThread (ONE_SECOND / 15);
 	Time = GetTimeCounter ();
@@ -1409,10 +1409,10 @@ InitPlanetSide (void)
 	{
 		SleepThreadUntil (Time + ONE_SECOND / 30);
 		Time = GetTimeCounter ();
-		SetSemaphore (GraphicsSem);
+		LockCrossThreadMutex (GraphicsLock);
 		DeltaSISGauges (-1, 0, 0);
 		DeltaLanderCrew (1, 0);
-		ClearSemaphore (GraphicsSem);
+		UnlockCrossThreadMutex (GraphicsLock);
 	}
 
 	SleepThreadUntil (Time + (ONE_SECOND / 15));
@@ -1423,9 +1423,9 @@ InitPlanetSide (void)
 	else
 		s.frame = SetAbsFrameIndex (s.frame,
 				(ANGLE_TO_FACING (FULL_CIRCLE) << 1) + 2);
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 	DrawStamp (&s);
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 
 	SleepThreadUntil (Time + (ONE_SECOND / 15));
 	Time = GetTimeCounter ();
@@ -1436,18 +1436,18 @@ InitPlanetSide (void)
 	{
 		s.frame = SetAbsFrameIndex (s.frame,
 				(ANGLE_TO_FACING (FULL_CIRCLE) << 1) + 3);
-		SetSemaphore (GraphicsSem);
+		LockCrossThreadMutex (GraphicsLock);
 		DrawStamp (&s);
-		ClearSemaphore (GraphicsSem);
+		UnlockCrossThreadMutex (GraphicsLock);
 
 		SleepThreadUntil (Time + (ONE_SECOND / 15));
 		Time = GetTimeCounter ();
 
 		s.frame = IncFrameIndex (s.frame);
 	}
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 	DrawStamp (&s);
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 
 	if (GET_GAME_STATE (IMPROVED_LANDER_CARGO))
 	{
@@ -1455,25 +1455,25 @@ InitPlanetSide (void)
 		Time = GetTimeCounter ();
 
 		s.frame = SetAbsFrameIndex (s.frame, 59);
-		SetSemaphore (GraphicsSem);
+		LockCrossThreadMutex (GraphicsLock);
 		DrawStamp (&s);
-		ClearSemaphore (GraphicsSem);
+		UnlockCrossThreadMutex (GraphicsLock);
 	}
 #ifndef SPIN_ON_LAUNCH
 	pSolarSysState->PauseRotate = 1;
 #endif
 	SleepThreadUntil (Time + (ONE_SECOND / 15));
 
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 	PlaySound (SetAbsSoundIndex (LanderSounds, LANDER_DEPARTS),
 			NotPositional (), NULL, GAME_SOUND_PRIORITY + 1);
 	SetContext (SpaceContext);
 	AnimateLaunch (LanderFrame[5], FALSE);
 #ifdef SPIN_ON_LAUNCH
 	pSolarSysState->PauseRotate = 1;
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 	TaskSwitch ();
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 #endif
 	// Adjust pSolarSysState->MenuState.first_item by a random jitter.
 #define RANDOM_MISS 64
@@ -1547,7 +1547,7 @@ InitPlanetSide (void)
 
 	SetContext (OldContext);
 
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 
 	SET_GAME_STATE (PLANETARY_LANDING, 1);
 }
@@ -1858,7 +1858,7 @@ ReturnToOrbit (PRECT pRect)
 {
 	CONTEXT OldContext;
 	
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 	OldContext = SetContext (SpaceContext);
 	SetContextClipRect (pRect);
 
@@ -1873,7 +1873,7 @@ ReturnToOrbit (PRECT pRect)
 
 	LoadIntoExtraScreen (pRect);
 	SetContext (OldContext);
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 
 //	SetPlanetTilt (0);
 }
@@ -1994,9 +1994,9 @@ PlanetSide (PMENU_STATE pMS)
 #endif /* NEVER */
 
 			--GLOBAL_SIS (NumLanders);
-			SetSemaphore (GraphicsSem);
+			LockCrossThreadMutex (GraphicsLock);
 			DrawLanders ();
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 
 			ReturnToOrbit (&r);
 		}
@@ -2029,7 +2029,7 @@ PlanetSide (PMENU_STATE pMS)
 			SleepThread (1);
 #endif
 
-			SetSemaphore (GraphicsSem);
+			LockCrossThreadMutex (GraphicsLock);
 			SetContext (SpaceContext);
 
 			AnimateLaunch (LanderFrame[6], TRUE);
@@ -2047,7 +2047,7 @@ PlanetSide (PMENU_STATE pMS)
 				DrawStorageBays (FALSE);
 			}
 
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 
 			GLOBAL_SIS (TotalBioMass) += PSD.BiologicalLevel;
 		}
@@ -2090,7 +2090,7 @@ InitLander (BYTE LanderFlags)
 {
 	RECT r;
 
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 
 	SetContext (RadarContext);
 	
@@ -2182,5 +2182,5 @@ InitLander (BYTE LanderFlags)
 
 	UnbatchGraphics ();
 
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 }
diff --git a/sc2/src/sc2code/planets/pl_stuff.c b/sc2/src/sc2code/planets/pl_stuff.c
index ea8f72c63..48c4bd811 100644
--- a/sc2/src/sc2code/planets/pl_stuff.c
+++ b/sc2/src/sc2code/planets/pl_stuff.c
@@ -74,7 +74,7 @@ RotatePlanet (int x, int dx, int dy, COUNT scale_amt, UBYTE zoom_from, PRECT zoo
 		dy += ((zoom_from & 0x02) ? 1 : -1) * dy * (base - scale_amt) / base;
 	}
 
-	//SetSemaphore (GraphicsSem);
+	//LockCrossThreadMutex (GraphicsLock);
 
 	// PauseRotate needs to be checked twice.   It is first
 	// checked at the rotate_planet_task function to bypass
@@ -82,7 +82,7 @@ RotatePlanet (int x, int dx, int dy, COUNT scale_amt, UBYTE zoom_from, PRECT zoo
 	// parts of te code.  It is checked here because it is possile
 	// that PauseRotate was set between then and now, and we don't
 	// want too push anything onto the DrawQueue in that case.
-	// If the setSemaphore is moved before the RenderLevelMasks call,
+	// If the LockCrossThreadMutex is moved before the RenderLevelMasks call,
 	// one of the two PauseRotate checks can be removed.
 	//if (((PSOLARSYS_STATE volatile)pSolarSysState)->PauseRotate !=1)
 	{
@@ -103,7 +103,7 @@ RotatePlanet (int x, int dx, int dy, COUNT scale_amt, UBYTE zoom_from, PRECT zoo
 		UnbatchGraphics ();
 		SetContext (OldContext);
 	}
-	//ClearSemaphore (GraphicsSem);
+	//UnlockCrossThreadMutex (GraphicsLock);
 	if (scale_amt && scale_amt != base)
 	{
 		GetFrameRect (pFrame[num_frames - 1], zoomr);
diff --git a/sc2/src/sc2code/planets/planets.c b/sc2/src/sc2code/planets/planets.c
index 9c82173b5..4338a5089 100644
--- a/sc2/src/sc2code/planets/planets.c
+++ b/sc2/src/sc2code/planets/planets.c
@@ -61,7 +61,7 @@ void
 LoadPlanet (BOOLEAN IsDefined)
 {
 	STAMP s;
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 
 	BatchGraphics ();
 	SetTransitionSource (NULL);
@@ -106,9 +106,9 @@ LoadPlanet (BOOLEAN IsDefined)
 	{
 		if (LOBYTE (LastActivity) == 0)
 		{
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 			DrawSISFrame ();
-			SetSemaphore (GraphicsSem);
+			LockCrossThreadMutex (GraphicsLock);
 		}
 		else
 		{
@@ -146,7 +146,7 @@ LoadPlanet (BOOLEAN IsDefined)
 		LoadIntoExtraScreen (&r);
 	}
 	
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 
 	if (!PLRPlaying ((MUSIC_REF)~0))
 	{
@@ -173,7 +173,7 @@ LoadPlanet (BOOLEAN IsDefined)
 		r.corner.y = SIS_ORG_Y;
 		r.extent.width = SIS_SCREEN_WIDTH;
 		r.extent.height = SIS_SCREEN_HEIGHT;
-		SetSemaphore (GraphicsSem);
+		LockCrossThreadMutex (GraphicsLock);
 		oldContext = SetContext (SpaceContext);
 		DrawStarBackGround (TRUE);
 		SetContext (oldContext);
@@ -183,7 +183,7 @@ LoadPlanet (BOOLEAN IsDefined)
 		ScreenTransition (3, &r);  // How does this work?
 		UnbatchGraphics ();
 		LoadIntoExtraScreen (&r);
-		ClearSemaphore (GraphicsSem);
+		UnlockCrossThreadMutex (GraphicsLock);
 	}
 }
 
@@ -201,7 +201,7 @@ FreePlanet (void)
 	}
 
 	StopMusic ();
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 
 	for (i = 0; i < sizeof (pSolarSysState->PlanetSideFrame)
 			/ sizeof (pSolarSysState->PlanetSideFrame[0]); ++i)
@@ -253,6 +253,6 @@ FreePlanet (void)
 	pSolarSysState->SysInfo.PlanetInfo.LanderFont = 0;
 	pSolarSysState->PauseRotate = 0;
 
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 }
 
diff --git a/sc2/src/sc2code/planets/plangen.c b/sc2/src/sc2code/planets/plangen.c
index 52b3d2f8e..12593b2a8 100644
--- a/sc2/src/sc2code/planets/plangen.c
+++ b/sc2/src/sc2code/planets/plangen.c
@@ -1411,14 +1411,14 @@ rotate_planet_task (void *data)
 		view_index = MAP_WIDTH;
 		do
 		{
-			// This SetSemaphore was placed before the RotatePlanet call
+			// This lock was placed before the RotatePlanet call
 			// To prevent the thread from being interrupted by the flash
 			// task while computing the Planet Frame.  This should help
 			// to smooth out the planet rotation animation.
-			// The PauseRotate needs to be placed after the SetSemaphore,
-			// to gaurantee that PauseRotate doesn't change while waiting
-			// to aquire the GraphicsSem
-			SetSemaphore (GraphicsSem);
+			// The PauseRotate needs to be placed after the lock,
+			// to guarantee that PauseRotate doesn't change while waiting
+			// to acquire the graphics lock
+			LockCrossThreadMutex (GraphicsLock);
 			if (*(volatile UBYTE *)&pSS->PauseRotate !=1
 //			if (((PSOLARSYS_STATE volatile)pSS)->MenuState.Initialized <= 3
 					&& !(GLOBAL (CurrentActivity) & CHECK_ABORT))
@@ -1441,7 +1441,7 @@ rotate_planet_task (void *data)
 			} else
 				view_index++;
 
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 			// If this frame hasn't been generted, generate it
 			if (! pSolarSysState->Orbit.isPFADefined[x]) {
 				RenderLevelMasks (x);
diff --git a/sc2/src/sc2code/planets/pstarmap.c b/sc2/src/sc2code/planets/pstarmap.c
index efe5c0b33..5375f01fa 100644
--- a/sc2/src/sc2code/planets/pstarmap.c
+++ b/sc2/src/sc2code/planets/pstarmap.c
@@ -73,7 +73,7 @@ flash_cursor_func(void *data)
 		CONTEXT OldContext;
 
 		TimeIn = GetTimeCounter ();
-		SetSemaphore (GraphicsSem);
+		LockCrossThreadMutex (GraphicsLock);
 		OldContext = SetContext (SpaceContext);
 
 		if (c == 0x00 || c == 0x1A)
@@ -86,7 +86,7 @@ flash_cursor_func(void *data)
 		SetContextForeGroundColor (OldColor);
 
 		SetContext (OldContext);
-		ClearSemaphore (GraphicsSem);
+		UnlockCrossThreadMutex (GraphicsLock);
 		SleepThreadUntil (TimeIn + (ONE_SECOND >> 4));
 	}
 	FinishTask (task);
@@ -254,7 +254,7 @@ DrawStarMap (COUNT race_update, PRECT pClipRect)
 	}
 	else
 	{
-		SetSemaphore (GraphicsSem);
+		LockCrossThreadMutex (GraphicsLock);
 		draw_cursor = TRUE;
 	}
 
@@ -528,7 +528,7 @@ wprintf ("%s\n", buf);
 	}
 
 	if (draw_cursor)
-		ClearSemaphore (GraphicsSem);
+		UnlockCrossThreadMutex (GraphicsLock);
 }
 
 static void
@@ -558,9 +558,9 @@ EraseCursor (COORD curs_x, COORD curs_y)
 #else /* NEW */
 	r.extent.height += r.corner.y & 1;
 	r.corner.y &= ~1;
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 	DrawStarMap (0, &r);
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 #endif /* OLD */
 }
 
@@ -730,11 +730,11 @@ DoMoveCursor (PMENU_STATE pMS)
 			}
 			else
 			{
-				SetSemaphore (GraphicsSem);
+				LockCrossThreadMutex (GraphicsLock);
 				EraseCursor (pt.x, pt.y);
 				// ClearDrawable ();
 				DrawCursor (s.origin.x, s.origin.y);
-				ClearSemaphore (GraphicsSem);
+				UnlockCrossThreadMutex (GraphicsLock);
 			}
 
 UpdateCursorInfo:
@@ -798,7 +798,7 @@ UpdateCursorInfo:
 					fuel_required = 0;
 				else
 					fuel_required = square_root (f) + (FUEL_TANK_SCALE >> 1);
-				SetSemaphore (GraphicsSem);
+				LockCrossThreadMutex (GraphicsLock);
 				DrawHyperCoords (pMenuState->first_item);
 				if (last_buf == (UNICODE) ~0
 						|| (buf[0] && !last_buf) || (!buf[0] && last_buf))
@@ -811,7 +811,7 @@ UpdateCursorInfo:
 						fuel_required / FUEL_TANK_SCALE,
 						(fuel_required % FUEL_TANK_SCALE) / 10);
 				DrawStatusMessage (buf);
-				ClearSemaphore (GraphicsSem);
+				UnlockCrossThreadMutex (GraphicsLock);
 			}
 		}
 	}
@@ -1106,7 +1106,7 @@ DoStarMap (void)
 	if (MenuState.first_item.x == ~0 && MenuState.first_item.y == ~0)
 		MenuState.first_item = universe;
 
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 	TaskSwitch ();
 
 	MenuState.InputFunc = DoMoveCursor;
@@ -1117,7 +1117,7 @@ DoStarMap (void)
 	if (GET_GAME_STATE (ARILOU_SPACE_SIDE) <= 1)
 		UpdateMap ();
 
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 	
 	DrawStarMap (0, (PRECT)-1);
 	transition_pending = FALSE;
@@ -1132,7 +1132,7 @@ DoStarMap (void)
 			UNIVERSE_TO_DISPY (pMenuState->first_item.y)
 			);
 	UnbatchGraphics ();
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 
 	OldMenuSounds = MenuSounds;
 	MenuSounds = 0;
@@ -1142,7 +1142,7 @@ DoStarMap (void)
 
 	pMenuState = 0;
 
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 
 	DrawHyperCoords (universe);
 	DrawSISMessage (NULL_PTR);
@@ -1166,7 +1166,7 @@ DoFlagshipCommands (PMENU_STATE pMS)
 	else
 	{
 		BOOLEAN select = CurrentMenuState.select;
-		SetSemaphore (GraphicsSem);
+		LockCrossThreadMutex (GraphicsLock);
 		while (*(volatile BYTE *)&pMS->CurState == 0
 				&& (*(volatile SIZE *)&pMS->Initialized & 1)
 				&& !(GLOBAL (CurrentActivity)
@@ -1174,11 +1174,11 @@ DoFlagshipCommands (PMENU_STATE pMS)
 				| CHECK_ABORT | CHECK_LOAD))
 				&& GLOBAL_SIS (CrewEnlisted) != (COUNT)~0)
 		{
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 			TaskSwitch ();
-			SetSemaphore (GraphicsSem);
+			LockCrossThreadMutex (GraphicsLock);
 		}
-		ClearSemaphore (GraphicsSem);
+		UnlockCrossThreadMutex (GraphicsLock);
 
 		if (pMS->CurState)
 		{
@@ -1199,9 +1199,9 @@ DoFlagshipCommands (PMENU_STATE pMS)
 				{
 					if (NewState != SCAN + 1 && NewState != (GAME_MENU) + 1)
 					{
-						SetSemaphore (GraphicsSem);
+						LockCrossThreadMutex (GraphicsLock);
 						SetFlashRect (NULL_PTR, (FRAME)0);
-						ClearSemaphore (GraphicsSem);
+						UnlockCrossThreadMutex (GraphicsLock);
 					}
 
 					switch (NewState - 1)
@@ -1247,7 +1247,7 @@ DoFlagshipCommands (PMENU_STATE pMS)
 						{
 							BOOLEAN AutoPilotSet;
 
-							SetSemaphore (GraphicsSem);
+							LockCrossThreadMutex (GraphicsLock);
 							if (++pMS->Initialized > 3) {
 								pSolarSysState->PauseRotate = 1;
 								RepairSISBorder ();
@@ -1258,7 +1258,7 @@ DoFlagshipCommands (PMENU_STATE pMS)
 							if (LOBYTE (GLOBAL (CurrentActivity)) == IN_HYPERSPACE
 									|| (GLOBAL (CurrentActivity) & CHECK_ABORT))
 							{
-								ClearSemaphore (GraphicsSem);
+								UnlockCrossThreadMutex (GraphicsLock);
 								return (FALSE);
 							}
 							else if (pMS->Initialized <= 3)
@@ -1266,16 +1266,16 @@ DoFlagshipCommands (PMENU_STATE pMS)
 								ZoomSystem ();
 								--pMS->Initialized;
 							}
-							ClearSemaphore (GraphicsSem);
+							UnlockCrossThreadMutex (GraphicsLock);
 
 							if (!AutoPilotSet && pMS->Initialized >= 3)
 							{
 								LoadPlanet (FALSE);
 								--pMS->Initialized;
 								pSolarSysState->PauseRotate = 0;
-								SetSemaphore (GraphicsSem);
+								LockCrossThreadMutex (GraphicsLock);
 								SetFlashRect ((PRECT)~0L, (FRAME)0);
-								ClearSemaphore (GraphicsSem);
+								UnlockCrossThreadMutex (GraphicsLock);
 								break;
 							}
 						}
@@ -1291,17 +1291,17 @@ DoFlagshipCommands (PMENU_STATE pMS)
 							else if (pMS->flash_task)
 							{
 								FreePlanet ();
-								SetSemaphore (GraphicsSem);
+								LockCrossThreadMutex (GraphicsLock);
 								LoadSolarSys ();
 								ValidateOrbits ();
 								ZoomSystem ();
-								ClearSemaphore (GraphicsSem);
+								UnlockCrossThreadMutex (GraphicsLock);
 							}
 
-							SetSemaphore (GraphicsSem);
+							LockCrossThreadMutex (GraphicsLock);
 							pMS->CurState = 0;
 							FlushInput ();
-							ClearSemaphore (GraphicsSem);
+							UnlockCrossThreadMutex (GraphicsLock);
 							break;
 					}
 				
@@ -1309,9 +1309,9 @@ DoFlagshipCommands (PMENU_STATE pMS)
 						;
 					else if (pMS->CurState)
 					{
-						SetSemaphore (GraphicsSem);
+						LockCrossThreadMutex (GraphicsLock);
 						SetFlashRect ((PRECT)~0L, (FRAME)0);
-						ClearSemaphore (GraphicsSem);
+						UnlockCrossThreadMutex (GraphicsLock);
 						if (select)
 						{
 							if (optWhichMenu != OPT_PC)
@@ -1322,9 +1322,9 @@ DoFlagshipCommands (PMENU_STATE pMS)
 					}
 					else
 					{
-						SetSemaphore (GraphicsSem);
+						LockCrossThreadMutex (GraphicsLock);
 						SetFlashRect (NULL_PTR, (FRAME)0);
-						ClearSemaphore (GraphicsSem);
+						UnlockCrossThreadMutex (GraphicsLock);
 						DrawMenuStateStrings (PM_STARMAP, -NAVIGATION);
 					}
 				}
diff --git a/sc2/src/sc2code/planets/report.c b/sc2/src/sc2code/planets/report.c
index ee47cd463..b2fe93871 100644
--- a/sc2/src/sc2code/planets/report.c
+++ b/sc2/src/sc2code/planets/report.c
@@ -94,7 +94,7 @@ MakeReport (SOUND ReadOutSounds, UNICODE *pStr, COUNT StrLen)
 	last_c = *pStr;
 
 	Sleepy = TRUE;
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 
 	FlushInput ();
 	goto InitPageCell;
@@ -148,9 +148,9 @@ MakeReport (SOUND ReadOutSounds, UNICODE *pStr, COUNT StrLen)
 						font_DrawText (&t);
 					else
 					{
-						SetSemaphore (GraphicsSem);
+						LockCrossThreadMutex (GraphicsLock);
 						font_DrawText (&t);
-						ClearSemaphore (GraphicsSem);
+						UnlockCrossThreadMutex (GraphicsLock);
 
 						PlaySound (ReadOutSounds, NotPositional (), NULL, GAME_SOUND_PRIORITY);
 
@@ -174,7 +174,7 @@ MakeReport (SOUND ReadOutSounds, UNICODE *pStr, COUNT StrLen)
 							else if (AnyButtonPress (TRUE))
 							{
 								Sleepy = FALSE;
-								SetSemaphore (GraphicsSem);
+								LockCrossThreadMutex (GraphicsLock);
 								BatchGraphics ();
 								break;
 							}
@@ -198,7 +198,7 @@ MakeReport (SOUND ReadOutSounds, UNICODE *pStr, COUNT StrLen)
 			if (!Sleepy)
 			{
 				UnbatchGraphics ();
-				ClearSemaphore (GraphicsSem);
+				UnlockCrossThreadMutex (GraphicsLock);
 			}
 
 			if (WaitAnyButtonOrQuit (TRUE))
@@ -210,17 +210,17 @@ InitPageCell:
 			row_cells = 0;
 			if (StrLen)
 			{
-				SetSemaphore (GraphicsSem);
+				LockCrossThreadMutex (GraphicsLock);
 				if (!Sleepy)
 					BatchGraphics ();
 				ClearReportArea();
 				SetContextForeGroundColor (BUILD_COLOR (MAKE_RGB15 (0, 0x1F, 0), 0xFF));
 				if (Sleepy)
-					ClearSemaphore (GraphicsSem);
+					UnlockCrossThreadMutex (GraphicsLock);
 			}
 		}
 	}
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 }
 
 void
@@ -268,11 +268,11 @@ DoDiscoveryReport (SOUND ReadOutSounds)
 #endif /* OLD */
 	SetContext (OldContext);
 
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 	FlushInput ();
 	while (AnyButtonPress (TRUE))
 		TaskSwitch ();
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 
 	if (pMenuState)
 		pMenuState->flash_rect0.corner = old_curs;
diff --git a/sc2/src/sc2code/planets/roster.c b/sc2/src/sc2code/planets/roster.c
index 7cc8f914f..64a745ffa 100644
--- a/sc2/src/sc2code/planets/roster.c
+++ b/sc2/src/sc2code/planets/roster.c
@@ -35,7 +35,7 @@ flash_ship_task(void *data)
 		COLOR OldColor;
 		CONTEXT OldContext;
 
-		SetSemaphore (GraphicsSem);
+		LockCrossThreadMutex (GraphicsLock);
 		s.origin = pMenuState->first_item;
 		StarShipPtr = (SHIP_FRAGMENTPTR)LockStarShip (
 				&GLOBAL (built_ship_q),
@@ -55,7 +55,7 @@ flash_ship_task(void *data)
 		DrawFilledStamp (&s);
 		SetContextForeGroundColor (OldColor);
 		SetContext (OldContext);
-		ClearSemaphore (GraphicsSem);
+		UnlockCrossThreadMutex (GraphicsLock);
 		SleepThreadUntil (TimeIn + ONE_SECOND / 15);
 		TimeIn = GetTimeCounter ();
 	}
@@ -212,9 +212,9 @@ DoModifyRoster (PMENU_STATE pMS)
 	if (GLOBAL (CurrentActivity) & CHECK_ABORT)
 	{
 		pMS->CurFrame = 0;
-		SetSemaphore (GraphicsSem);
+		LockCrossThreadMutex (GraphicsLock);
 		RosterCleanup (pMS);
-		ClearSemaphore (GraphicsSem);
+		UnlockCrossThreadMutex (GraphicsLock);
 
 		return (FALSE);
 	}
@@ -231,24 +231,24 @@ DoModifyRoster (PMENU_STATE pMS)
 		pMS->Initialized = TRUE;
 
 		pMS->CurState = NewState = 0;
-		SetSemaphore (GraphicsSem);
+		LockCrossThreadMutex (GraphicsLock);
 		SetContext (StatusContext);
 		goto SelectSupport;
 	}
 	else if (cancel && !(pMS->CurState & SHIP_TOGGLE))
 	{
-		SetSemaphore (GraphicsSem);
+		LockCrossThreadMutex (GraphicsLock);
 		SetFlashRect (NULL_PTR, (FRAME)0);
 		RosterCleanup (pMS);
 		pMS->CurFrame = 0;
 		DrawStatusMessage (NULL_PTR);
-		ClearSemaphore (GraphicsSem);
+		UnlockCrossThreadMutex (GraphicsLock);
 
 		return (FALSE);
 	}
 	else if (select || cancel)
 	{
-		SetSemaphore (GraphicsSem);
+		LockCrossThreadMutex (GraphicsLock);
 		pMS->CurState ^= SHIP_TOGGLE;
 		if (!(pMS->CurState & SHIP_TOGGLE))
 			SetFlashRect (NULL_PTR, (FRAME)0);
@@ -263,7 +263,7 @@ DoModifyRoster (PMENU_STATE pMS)
 			SetContext (StatusContext);
 			SetFlashRect (&r, (FRAME)0);
 		}
-		ClearSemaphore (GraphicsSem);
+		UnlockCrossThreadMutex (GraphicsLock);
 	}
 	else if (pMS->CurState & SHIP_TOGGLE)
 	{
@@ -272,9 +272,9 @@ DoModifyRoster (PMENU_STATE pMS)
 			sy = -1;
 			if (GLOBAL_SIS (CrewEnlisted))
 			{
-				SetSemaphore (GraphicsSem);
+				LockCrossThreadMutex (GraphicsLock);
 				DeltaSupportCrew (1);
-				ClearSemaphore (GraphicsSem);
+				UnlockCrossThreadMutex (GraphicsLock);
 			}
 		}
 		else if (down)
@@ -283,9 +283,9 @@ DoModifyRoster (PMENU_STATE pMS)
 			if (GLOBAL_SIS (CrewEnlisted)
 					< GetCPodCapacity (NULL_PTR))
 			{
-				SetSemaphore (GraphicsSem);
+				LockCrossThreadMutex (GraphicsLock);
 				DeltaSupportCrew (-1);
-				ClearSemaphore (GraphicsSem);
+				UnlockCrossThreadMutex (GraphicsLock);
 			}
 		}
 	}
@@ -335,7 +335,7 @@ DoModifyRoster (PMENU_STATE pMS)
 
 		if (NewState != pMS->CurState)
 		{
-			SetSemaphore (GraphicsSem);
+			LockCrossThreadMutex (GraphicsLock);
 			SetContext (StatusContext);
 			s.origin = pMS->first_item;
 			StarShipPtr = (SHIP_FRAGMENTPTR)LockStarShip (
@@ -354,7 +354,7 @@ SelectSupport:
 			pMS->CurFrame = (FRAME)MatchSupportShip (pMS);
 
 			DeltaSupportCrew (0);
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 
 			pMS->CurState = NewState;
 		}
diff --git a/sc2/src/sc2code/planets/scan.c b/sc2/src/sc2code/planets/scan.c
index ffbd2f6ce..43c2064fe 100644
--- a/sc2/src/sc2code/planets/scan.c
+++ b/sc2/src/sc2code/planets/scan.c
@@ -68,7 +68,7 @@ EraseCoarseScan (void)
 	const int leftScanOffset  = 5;
 	const int rightScanOffset = 50;
 
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 	SetContext (SpaceContext);
 
 	r.corner.x = (SIS_SCREEN_WIDTH >> 1) - (160 >> 1);
@@ -88,7 +88,7 @@ EraseCoarseScan (void)
 	r.extent.width = rightScanWidth;
 	RepairBackRect (&r);
 
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 }
 
 static void
@@ -113,7 +113,7 @@ PrintCoarseScanPC (void)
 	RECT r;
 	UNICODE buf[40];
 
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 	SetContext (SpaceContext);
 
 	if (CurStarDescPtr->Index == SOL_DEFINED)
@@ -176,7 +176,7 @@ PrintCoarseScanPC (void)
 	SetContextFont (MicroFont);
 	font_DrawText (&t);
 	SetContextFont (TinyFont);
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 
 #define LEFT_SIDE_BASELINE_X_PC 5
 #define RIGHT_SIDE_BASELINE_X_PC (SIS_SCREEN_WIDTH - 75)
@@ -185,7 +185,7 @@ PrintCoarseScanPC (void)
 	t.baseline.y = SCAN_BASELINE_Y_PC;
 	t.align = ALIGN_LEFT;
 
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 	t.pStr = buf;
 	PrintScanTitlePC (&t, &r, "Orbit: ", LEFT_SIDE_BASELINE_X_PC);
 	temp = (SIZE)((pSolarSysState->SysInfo.PlanetInfo.PlanetToSunDist * 100L
@@ -197,9 +197,9 @@ PrintCoarseScanPC (void)
 	t.CharCount = (COUNT)~0;
 	font_DrawText (&t);
 	t.baseline.y += SCAN_LEADING_PC;
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 	t.pStr = buf;
 	PrintScanTitlePC (&t, &r, "Atmo: ", LEFT_SIDE_BASELINE_X_PC);
 	if (pSolarSysState->SysInfo.PlanetInfo.AtmoDensity == GAS_GIANT_ATMOSPHERE)
@@ -218,18 +218,18 @@ PrintCoarseScanPC (void)
 	t.CharCount = (COUNT)~0;
 	font_DrawText (&t);
 	t.baseline.y += SCAN_LEADING_PC;
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 	t.pStr = buf;
 	PrintScanTitlePC (&t, &r, "Temp: ", LEFT_SIDE_BASELINE_X_PC);
 	wsprintf (buf, "%d^ c", pSolarSysState->SysInfo.PlanetInfo.SurfaceTemperature);
 	t.CharCount = (COUNT)~0;
 	font_DrawText (&t);
 	t.baseline.y += SCAN_LEADING_PC;
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 	t.pStr = buf;
 	PrintScanTitlePC (&t, &r, "Weather: ", LEFT_SIDE_BASELINE_X_PC);
 	if (pSolarSysState->SysInfo.PlanetInfo.AtmoDensity == 0)
@@ -239,9 +239,9 @@ PrintCoarseScanPC (void)
 	t.CharCount = (COUNT)~0;
 	font_DrawText (&t);
 	t.baseline.y += SCAN_LEADING_PC;
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 	t.pStr = buf;
 	PrintScanTitlePC (&t, &r, "Tectonics: ", LEFT_SIDE_BASELINE_X_PC);
 	if (PLANSIZE (pSolarSysState->SysInfo.PlanetInfo.PlanDataPtr->Type) == GAS_GIANT)
@@ -250,11 +250,11 @@ PrintCoarseScanPC (void)
 	wsprintf (buf, "Class %u", pSolarSysState->SysInfo.PlanetInfo.Tectonics + 1);
 	t.CharCount = (COUNT)~0;
 	font_DrawText (&t);
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 
 	t.baseline.y = SCAN_BASELINE_Y_PC;
 
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 	t.pStr = buf;
 	PrintScanTitlePC (&t, &r, "Mass: ", RIGHT_SIDE_BASELINE_X_PC);
 	{
@@ -274,9 +274,9 @@ PrintCoarseScanPC (void)
 	t.CharCount = (COUNT)~0;
 	font_DrawText (&t);
 	t.baseline.y += SCAN_LEADING_PC;
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 	t.pStr = buf;
 	PrintScanTitlePC (&t, &r, "Radius: ", RIGHT_SIDE_BASELINE_X_PC);
 	if ((temp = pSolarSysState->SysInfo.PlanetInfo.PlanetRadius) >= 10 * 100)
@@ -286,9 +286,9 @@ PrintCoarseScanPC (void)
 	t.CharCount = (COUNT)~0;
 	font_DrawText (&t);
 	t.baseline.y += SCAN_LEADING_PC;
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 	t.pStr = buf;
 	PrintScanTitlePC (&t, &r, "Gravity: ", RIGHT_SIDE_BASELINE_X_PC);
 	if ((temp = pSolarSysState->SysInfo.PlanetInfo.SurfaceGravity) >= 10 * 100)
@@ -302,9 +302,9 @@ PrintCoarseScanPC (void)
 	t.CharCount = (COUNT)~0;
 	font_DrawText (&t);
 	t.baseline.y += SCAN_LEADING_PC;
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 	t.pStr = buf;
 	PrintScanTitlePC (&t, &r, "Day: ", RIGHT_SIDE_BASELINE_X_PC);
 	if (pSolarSysState->SysInfo.PlanetInfo.RotationPeriod < 240 * 10)
@@ -321,9 +321,9 @@ PrintCoarseScanPC (void)
 	t.CharCount = (COUNT)~0;
 	font_DrawText (&t);
 	t.baseline.y += SCAN_LEADING_PC;
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 	t.pStr = buf;
 	PrintScanTitlePC (&t, &r, "Tilt: ", RIGHT_SIDE_BASELINE_X_PC);
 	if ((temp = pSolarSysState->SysInfo.PlanetInfo.AxialTilt) < 0)
@@ -331,7 +331,7 @@ PrintCoarseScanPC (void)
 	wsprintf (buf, "%u^", temp);
 	t.CharCount = (COUNT)~0;
 	font_DrawText (&t);
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 }
 
 static void
@@ -344,7 +344,7 @@ PrintCoarseScan3DO (void)
 	UNICODE buf[40];
 	extern FRAME SpaceJunkFrame;
 
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 	SetContext (SpaceContext);
 
 	if (CurStarDescPtr->Index == SOL_DEFINED)
@@ -411,7 +411,7 @@ PrintCoarseScan3DO (void)
 	s.frame = SetAbsFrameIndex (SpaceJunkFrame, 20);
 	DrawStamp (&s);
 
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 
 #define LEFT_SIDE_BASELINE_X (27 + (16 - SAFE_X))
 #define RIGHT_SIDE_BASELINE_X (SIS_SCREEN_WIDTH - LEFT_SIDE_BASELINE_X)
@@ -421,7 +421,7 @@ PrintCoarseScan3DO (void)
 	t.baseline.y = SCAN_BASELINE_Y;
 	t.align = ALIGN_LEFT;
 
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 	t.pStr = buf;
 	temp = (SIZE)((pSolarSysState->SysInfo.PlanetInfo.PlanetToSunDist * 100L
 			+ (EARTH_RADIUS >> 1)) / EARTH_RADIUS);
@@ -432,9 +432,9 @@ PrintCoarseScan3DO (void)
 	t.CharCount = (COUNT)~0;
 	font_DrawText (&t);
 	t.baseline.y += SCAN_LEADING;
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 	t.pStr = buf;
 	if (pSolarSysState->SysInfo.PlanetInfo.AtmoDensity == GAS_GIANT_ATMOSPHERE)
 		wsprintf (buf, "\x7f");
@@ -450,26 +450,26 @@ PrintCoarseScan3DO (void)
 	t.CharCount = (COUNT)~0;
 	font_DrawText (&t);
 	t.baseline.y += SCAN_LEADING;
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 	t.pStr = buf;
 	wsprintf (buf, "%d^", pSolarSysState->SysInfo.PlanetInfo.SurfaceTemperature);
 	t.CharCount = (COUNT)~0;
 	font_DrawText (&t);
 	t.baseline.y += SCAN_LEADING;
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 	t.pStr = buf;
 	wsprintf (buf, "<%u>", pSolarSysState->SysInfo.PlanetInfo.AtmoDensity == 0
 			? 0 : (pSolarSysState->SysInfo.PlanetInfo.Weather + 1));
 	t.CharCount = (COUNT)~0;
 	font_DrawText (&t);
 	t.baseline.y += SCAN_LEADING;
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 	t.pStr = buf;
 	wsprintf (buf, "<%u>",
 			PLANSIZE (
@@ -478,13 +478,13 @@ PrintCoarseScan3DO (void)
 			? 0 : (pSolarSysState->SysInfo.PlanetInfo.Tectonics + 1));
 	t.CharCount = (COUNT)~0;
 	font_DrawText (&t);
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 
 	t.baseline.x = RIGHT_SIDE_BASELINE_X;
 	t.baseline.y = SCAN_BASELINE_Y;
 	t.align = ALIGN_RIGHT;
 
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 	t.pStr = buf;
 	{
 		DWORD tr;
@@ -503,9 +503,9 @@ PrintCoarseScan3DO (void)
 	t.CharCount = (COUNT)~0;
 	font_DrawText (&t);
 	t.baseline.y += SCAN_LEADING;
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 	t.pStr = buf;
 	if ((temp = pSolarSysState->SysInfo.PlanetInfo.PlanetRadius) >= 10 * 100)
 		wsprintf (buf, "%u.%u&", temp / 100, (temp / 10) % 10);
@@ -514,9 +514,9 @@ PrintCoarseScan3DO (void)
 	t.CharCount = (COUNT)~0;
 	font_DrawText (&t);
 	t.baseline.y += SCAN_LEADING;
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 	t.pStr = buf;
 	if ((temp = pSolarSysState->SysInfo.PlanetInfo.SurfaceGravity) >= 10 * 100)
 		wsprintf (buf, "%u.%u&", temp / 100, (temp / 10) % 10);
@@ -529,9 +529,9 @@ PrintCoarseScan3DO (void)
 	t.CharCount = (COUNT)~0;
 	font_DrawText (&t);
 	t.baseline.y += SCAN_LEADING;
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 	t.pStr = buf;
 	if ((temp = pSolarSysState->SysInfo.PlanetInfo.AxialTilt) < 0)
 		temp = -temp;
@@ -539,9 +539,9 @@ PrintCoarseScan3DO (void)
 	t.CharCount = (COUNT)~0;
 	font_DrawText (&t);
 	t.baseline.y += SCAN_LEADING;
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 	t.pStr = buf;
 	if (pSolarSysState->SysInfo.PlanetInfo.RotationPeriod < 240 * 10)
 	{
@@ -556,7 +556,7 @@ PrintCoarseScan3DO (void)
 	}
 	t.CharCount = (COUNT)~0;
 	font_DrawText (&t);
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 }
 
 static void
@@ -569,7 +569,7 @@ SetPlanetLoc (POINT new_pt)
 	new_pt.x >>= MAG_SHIFT;
 	new_pt.y >>= MAG_SHIFT;
 
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 	SetContext (ScanContext);
 	s.origin.x = pMenuState->flash_rect0.corner.x - (FLASH_WIDTH >> 1);
 	s.origin.y = pMenuState->flash_rect0.corner.y - (FLASH_HEIGHT >> 1);
@@ -583,7 +583,7 @@ SetPlanetLoc (POINT new_pt)
 	r.extent.width = FLASH_WIDTH;
 	r.extent.height = FLASH_HEIGHT;
 	LoadDisplayPixmap (&r, pMenuState->flash_frame0);
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 	
 	TaskSwitch ();
 }
@@ -609,7 +609,7 @@ flash_planet_loc_func(void *data)
 		DWORD T;
 		CONTEXT OldContext;
 
-		SetSemaphore (GraphicsSem);
+		LockCrossThreadMutex (GraphicsLock);
 		T = GetTimeCounter ();
 		if (p.Object.Stamp.origin.x != pMenuState->flash_rect0.corner.x
 				|| p.Object.Stamp.origin.y != pMenuState->flash_rect0.corner.y)
@@ -621,7 +621,7 @@ flash_planet_loc_func(void *data)
 		{
 			if (T < TimeIn)
 			{
-				ClearSemaphore (GraphicsSem);
+				UnlockCrossThreadMutex (GraphicsLock);
 				TaskSwitch ();
 
 				continue;
@@ -639,7 +639,7 @@ flash_planet_loc_func(void *data)
 		SetContext (OldContext);
 
 		TimeIn = T + (ONE_SECOND >> 4);
-		ClearSemaphore (GraphicsSem);
+		UnlockCrossThreadMutex (GraphicsLock);
 		
 		TaskSwitch ();
 	}
@@ -680,7 +680,7 @@ PickPlanetSide (PMENU_STATE pMS)
 
 			pMS->Initialized = TRUE;
 
-			SetSemaphore (GraphicsSem);
+			LockCrossThreadMutex (GraphicsLock);
 			SetContext (ScanContext);
 			pMenuState->flash_rect0.corner.x =
 					pSolarSysState->MenuState.first_item.x >> MAG_SHIFT;
@@ -694,7 +694,7 @@ PickPlanetSide (PMENU_STATE pMS)
 			LoadDisplayPixmap (&r, pMenuState->flash_frame0);
 
 			SetFlashRect (NULL_PTR, (FRAME)0);
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 
 			InitLander (0);
 
@@ -709,9 +709,9 @@ PickPlanetSide (PMENU_STATE pMS)
 		MenuSounds = (SOUND)pMS->CurFrame;
 		pMS->CurFrame = 0;
 
-		SetSemaphore (GraphicsSem);
+		LockCrossThreadMutex (GraphicsLock);
 		DrawStatusMessage (NULL_PTR);
-		ClearSemaphore (GraphicsSem);
+		UnlockCrossThreadMutex (GraphicsLock);
 
 		FlushInput ();
 		if (pMenuState->flash_task)
@@ -735,13 +735,13 @@ PickPlanetSide (PMENU_STATE pMS)
 
 			EraseCoarseScan ();
 
-			SetSemaphore (GraphicsSem);
+			LockCrossThreadMutex (GraphicsLock);
 			DeltaSISGauges (0, -(SIZE)fuel_required, 0);
 			SetContext (ScanContext);
 			s.origin = pMenuState->flash_rect0.corner;
 			s.frame = SetAbsFrameIndex (misc_data, FLASH_INDEX);
 			DrawStamp (&s);
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 
 			PlanetSide (pMS);
 			if (GLOBAL (CurrentActivity) & CHECK_ABORT)
@@ -796,9 +796,9 @@ PickPlanetSide (PMENU_STATE pMS)
 		}
 
 		DrawMenuStateStrings (PM_MIN_SCAN, DISPATCH_SHUTTLE);
-		SetSemaphore (GraphicsSem);
+		LockCrossThreadMutex (GraphicsLock);
 		SetFlashRect ((PRECT)~0L, (FRAME)0);
-		ClearSemaphore (GraphicsSem);
+		UnlockCrossThreadMutex (GraphicsLock);
 
 ExitPlanetSide:
 		if (pMS->CurFrame)
@@ -962,12 +962,12 @@ DoScan (PMENU_STATE pMS)
 	}
 	else if (cancel || (select && pMS->CurState == EXIT_SCAN))
 	{
-		SetSemaphore (GraphicsSem);
+		LockCrossThreadMutex (GraphicsLock);
 		SetContext (SpaceContext);
 		BatchGraphics ();
 		DrawPlanet (SIS_SCREEN_WIDTH - MAP_WIDTH, SIS_SCREEN_HEIGHT - MAP_HEIGHT, 0, 0);
 		UnbatchGraphics ();
-		ClearSemaphore (GraphicsSem);
+		UnlockCrossThreadMutex (GraphicsLock);
 
 		EraseCoarseScan ();
 // DrawMenuStateStrings (PM_SCAN, SCAN);
@@ -1004,18 +1004,18 @@ DoScan (PMENU_STATE pMS)
 					GAME_STRING (NAVIGATION_STRING_BASE + 5),
 					fuel_required / FUEL_TANK_SCALE,
 					((fuel_required % FUEL_TANK_SCALE) + 5) / 10);
-			SetSemaphore (GraphicsSem);
+			LockCrossThreadMutex (GraphicsLock);
 			ClearSISRect (CLEAR_SIS_RADAR);
 			DrawStatusMessage (buf);
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 
-			SetSemaphore (GraphicsSem);
+			LockCrossThreadMutex (GraphicsLock);
 			SetContext (ScanContext);
 			BatchGraphics ();
 			DrawPlanet (0, 0, 0, 0);
 			DrawScannedObjects (FALSE);
 			UnbatchGraphics ();
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 		
 			pMS->Initialized = FALSE;
 			pMS->CurFrame = 0;
@@ -1048,7 +1048,7 @@ DoScan (PMENU_STATE pMS)
 		pMS->delta_item = (SIZE)pSolarSysState->CurNode;
 		t.pStr = GAME_STRING (SCAN_STRING_BASE + min_scan);
 
-		SetSemaphore (GraphicsSem);
+		LockCrossThreadMutex (GraphicsLock);
 		SetContext (SpaceContext);
 		r.corner.x = 0;
 		r.corner.y = t.baseline.y - 10;
@@ -1078,7 +1078,7 @@ DoScan (PMENU_STATE pMS)
 		font_DrawText (&t);
 
 		SetContext (ScanContext);
-		ClearSemaphore (GraphicsSem);
+		UnlockCrossThreadMutex (GraphicsLock);
 
 	{
 		DWORD rgb;
@@ -1096,15 +1096,15 @@ DoScan (PMENU_STATE pMS)
 				break;
 		}
 
-		SetSemaphore (GraphicsSem);
+		LockCrossThreadMutex (GraphicsLock);
 		BatchGraphics ();
 		DrawPlanet (0, 0, 0, 0);
 		UnbatchGraphics ();
-		ClearSemaphore (GraphicsSem);
+		UnlockCrossThreadMutex (GraphicsLock);
 
 		PressState = AnyButtonPress (TRUE);
 		WaitTime = (ONE_SECOND << 1) / MAP_HEIGHT;
-//		SetSemaphore (GraphicsSem);
+//		LockCrossThreadMutex (GraphicsLock);
 		TimeIn = GetTimeCounter ();
 		for (i = 0; i < MAP_HEIGHT + NUM_FLASH_COLORS + 1; i++)
 		{
@@ -1116,7 +1116,7 @@ DoScan (PMENU_STATE pMS)
 			}
 			if (ButtonState)
 				i = -i;
-			SetSemaphore (GraphicsSem);
+			LockCrossThreadMutex (GraphicsLock);
 			BatchGraphics ();
 			DrawPlanet (0, 0, i, rgb);
 			if (i < 0) 
@@ -1124,19 +1124,19 @@ DoScan (PMENU_STATE pMS)
 			if (pMS->delta_item)
 				DrawScannedStuff (i, min_scan);
 			UnbatchGraphics ();
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 //			FlushGraphics ();
 			SleepThreadUntil (TimeIn + WaitTime);
 			TimeIn = GetTimeCounter ();
 		}
-//		ClearSemaphore (GraphicsSem);
+//		UnlockCrossThreadMutex (GraphicsLock);
 		pSolarSysState->Tint_rgb = 0;
 
 	}
 
 		} while (++min_scan <= max_scan);
 
-		SetSemaphore (GraphicsSem);
+		LockCrossThreadMutex (GraphicsLock);
 		SetContext (SpaceContext);
 		r.corner.x = 0;
 		r.corner.y = (SIS_SCREEN_HEIGHT - MAP_HEIGHT - 7) - 10;
@@ -1149,12 +1149,12 @@ DoScan (PMENU_STATE pMS)
 		{
 			DrawPlanet (0, 0, 0, 0);
 			DrawScannedObjects (FALSE);
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 
 			DrawMenuStateStrings (PM_MIN_SCAN, pMS->CurState = DISPATCH_SHUTTLE);
 		}
 		else
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 			
 		pSolarSysState->MenuState.Initialized -= 4;
 		pSolarSysState->PauseRotate = 0;
@@ -1208,7 +1208,7 @@ ScanSystem (void)
 		pSolarSysState->MenuState.first_item.x = (MAP_WIDTH >> 1) << MAG_SHIFT;
 		pSolarSysState->MenuState.first_item.y = (MAP_HEIGHT >> 1) << MAG_SHIFT;
 
-		SetSemaphore (GraphicsSem);
+		LockCrossThreadMutex (GraphicsLock);
 		ScanContext = CaptureContext (CreateContext ());
 		SetContext (ScanContext);
 		MenuState.flash_rect0.extent.width = FLASH_WIDTH;
@@ -1224,7 +1224,7 @@ ScanSystem (void)
 		r.extent.height = MAP_HEIGHT;
 		SetContextClipRect (&r);
 		DrawScannedObjects (FALSE);
-		ClearSemaphore (GraphicsSem);
+		UnlockCrossThreadMutex (GraphicsLock);
 	}
 
 	DrawMenuStateStrings (PM_MIN_SCAN, MenuState.CurState);
@@ -1240,12 +1240,12 @@ ScanSystem (void)
 
 	if (ScanContext)
 	{
-		SetSemaphore (GraphicsSem);
+		LockCrossThreadMutex (GraphicsLock);
 		SetContext (SpaceContext);
 		DestroyDrawable (ReleaseDrawable (MenuState.flash_frame0));
 		DestroyContext (ReleaseContext (ScanContext));
 		ScanContext = 0;
-		ClearSemaphore (GraphicsSem);
+		UnlockCrossThreadMutex (GraphicsLock);
 	}
 }
 
diff --git a/sc2/src/sc2code/planets/solarsys.c b/sc2/src/sc2code/planets/solarsys.c
index 055d6f62b..e86bd5a4d 100644
--- a/sc2/src/sc2code/planets/solarsys.c
+++ b/sc2/src/sc2code/planets/solarsys.c
@@ -339,18 +339,18 @@ FreeSolarSys (void)
 		{			
 			ConcludeTask (pSolarSysState->MenuState.flash_task);
 			pSolarSysState->MenuState.flash_task = 0;
-			SetSemaphore (GraphicsSem);
+			LockCrossThreadMutex (GraphicsLock);
 			if (!(GLOBAL (CurrentActivity) & (CHECK_ABORT | CHECK_LOAD)))
 			{
 				extern void SaveFlagshipState (void);
 
 				SaveFlagshipState ();
 			}
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 		}
 	}
 
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 
 	SetContext (SpaceContext);
 
@@ -358,7 +358,7 @@ FreeSolarSys (void)
 
 //    FreeIPData ();
 
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 }
 
 static void
@@ -1024,7 +1024,7 @@ int IPtask_func(void* data)
 		RECT r;
 
 		InnerSystem = FALSE;
-		SetSemaphore (GraphicsSem);
+		LockCrossThreadMutex (GraphicsLock);
 		while ((pSolarSysState->MenuState.Initialized > 1
 				|| (GLOBAL (CurrentActivity)
 				& (START_ENCOUNTER | END_INTERPLANETARY
@@ -1033,15 +1033,15 @@ int IPtask_func(void* data)
 				&& !Task_ReadState (task, TASK_EXIT))
 		{
 			select = cancel = FALSE;
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 			TaskSwitch ();
-			SetSemaphore (GraphicsSem);
+			LockCrossThreadMutex (GraphicsLock);
 			NextTime = GetTimeCounter ();
 		}
 
 		if (Task_ReadState (task, TASK_EXIT))
 		{
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 			break;
 		}
 
@@ -1163,7 +1163,7 @@ TheMess:
 		}
 
 		SetContext (OldContext);
-		ClearSemaphore (GraphicsSem);
+		UnlockCrossThreadMutex (GraphicsLock);
 
 		if (Task_ReadState (task, TASK_EXIT))
 		{
@@ -1190,20 +1190,20 @@ TheMess:
 			MenuTransition = DEBOUNCE_DELAY;
 			SuspendGameClock ();
 
-			SetSemaphore (GraphicsSem);
+			LockCrossThreadMutex (GraphicsLock);
 			DrawStatusMessage (NULL_PTR);
 			if (LastActivity == CHECK_LOAD)
 				pSolarSysState->MenuState.CurState = (ROSTER + 1) + 1;
 			else
 			{
-				ClearSemaphore (GraphicsSem);
+				UnlockCrossThreadMutex (GraphicsLock);
 				DrawMenuStateStrings (PM_STARMAP, STARMAP);
-				SetSemaphore (GraphicsSem);
+				LockCrossThreadMutex (GraphicsLock);
 				pSolarSysState->MenuState.CurState = STARMAP + 1;
 			}
 			SetFlashRect ((PRECT)~0L, (FRAME)0);
 			FlushInput ();
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 		}
 	}
 	FinishTask (task);
@@ -1213,10 +1213,10 @@ TheMess:
 static void
 DrawInnerSystem (void)
 {
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 	DrawSISTitle (GLOBAL_SIS (PlanetName));
 	DrawSystem (pSolarSysState->pBaseDesc->pPrevDesc->radius, TRUE);
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 }
 
 BOOLEAN
@@ -1276,7 +1276,7 @@ StartGroups:
 		{
 			DrawMenuStateStrings (PM_STARMAP, -(PM_NAVIGATE - PM_SCAN));
 
-			SetSemaphore (GraphicsSem);
+			LockCrossThreadMutex (GraphicsLock);
 			RepairSISBorder ();
 
 			InitDisplayList ();
@@ -1293,7 +1293,7 @@ StartGroups:
 			pSolarSysState->MenuState.flash_task =
 					AssignTask (IPtask_func, 6144,
 					"flash solar system menu");
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 
 			if (!PLRPlaying ((MUSIC_REF)~0) && LastActivity != CHECK_LOAD)
 			{
@@ -1308,14 +1308,14 @@ StartGroups:
 						draw_sys_flags &= ~UNBATCH_SYS;
 						UnbatchGraphics ();
 					}
-					SetSemaphore (GraphicsSem);
+					LockCrossThreadMutex (GraphicsLock);
 					while (pSolarSysState->SunDesc[0].radius == (MAX_ZOOM_RADIUS << 1))
 					{
-						ClearSemaphore (GraphicsSem);
+						UnlockCrossThreadMutex (GraphicsLock);
 						TaskSwitch ();
-						SetSemaphore (GraphicsSem);
+						LockCrossThreadMutex (GraphicsLock);
 					}
-					ClearSemaphore (GraphicsSem);
+					UnlockCrossThreadMutex (GraphicsLock);
 					XFormColorMap ((COLORMAPPTR)clut_buf, ONE_SECOND / 2);
 				}
 			}
@@ -1368,11 +1368,11 @@ StartGroups:
 		else
 		{
 			DrawMenuStateStrings (PM_SCAN, SCAN);
-			SetSemaphore (GraphicsSem);
+			LockCrossThreadMutex (GraphicsLock);
 			pSolarSysState->MenuState.CurState = SCAN + 1;
 			SetFlashRect ((PRECT)~0L, (FRAME)0);
 			FlushInput ();
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 		}
 	}
 }
@@ -1383,11 +1383,11 @@ InitSolarSys (void)
 	BOOLEAN InnerSystem;
 	BOOLEAN Reentry;
 
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 
 	LoadIPData ();
 	LoadLanderData ();
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 
 	pSolarSysState->MenuState.InputFunc = DoFlagshipCommands;
 
@@ -1440,23 +1440,23 @@ InitSolarSys (void)
 			}
 			else
 			{
-				SetSemaphore (GraphicsSem);
+				LockCrossThreadMutex (GraphicsLock);
 				ClearSISRect (DRAW_SIS_DISPLAY);
-				ClearSemaphore (GraphicsSem);
+				UnlockCrossThreadMutex (GraphicsLock);
 
 				LastActivity &= ~CHECK_LOAD;
 			}
 		}
 
-		// Enabled SetSemaphore and ClearSemaphore again, as in 3DO code originally.
+		// Enabled graphics synchronization again, as in 3DO code originally.
 		// This should fix the 'entering star' lockup/messed graphics problems.
 		// 2002/11/30 by Mika
-		SetSemaphore (GraphicsSem);
+		LockCrossThreadMutex (GraphicsLock);
 		DrawSISMessage (NULL_PTR);
 		SetContext (SpaceContext);
 		SetContextFGFrame (Screen);
 		SetContextBackGroundColor (BLACK_COLOR);
-		ClearSemaphore (GraphicsSem);
+		UnlockCrossThreadMutex (GraphicsLock);
 
 		if (InnerSystem)
 		{
@@ -1473,9 +1473,9 @@ InitSolarSys (void)
 		}
 		else
 		{
-			SetSemaphore (GraphicsSem);
+			LockCrossThreadMutex (GraphicsLock);
 			DrawHyperCoords (CurStarDescPtr->star_pt); /* Adjust position */
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 
 					/* force a redraw */
 			pSolarSysState->SunDesc[0].radius = MAX_ZOOM_RADIUS << 1;
diff --git a/sc2/src/sc2code/restart.c b/sc2/src/sc2code/restart.c
index ff009257f..4c084cd3b 100644
--- a/sc2/src/sc2code/restart.c
+++ b/sc2/src/sc2code/restart.c
@@ -53,7 +53,7 @@ DrawRestartMenu (BYTE OldState, BYTE NewState, FRAME f)
 	TEXT t;
 	UNICODE buf[64];
 
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 	SetContext (ScreenContext);
 	r.corner.x = r.corner.y = r.extent.width = r.extent.height = 0;
 	SetContextClipRect (&r);
@@ -76,7 +76,7 @@ DrawRestartMenu (BYTE OldState, BYTE NewState, FRAME f)
 	SetContextForeGroundColor (WHITE_COLOR);
 	font_DrawText (&t);
 
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 	(void) OldState;  /* Satisfying compiler (unused parameter) */
 }
 
@@ -155,9 +155,9 @@ else if (InputState & DEVICE_EXIT) return (FALSE);
 				break;
 		}
 
-		SetSemaphore (GraphicsSem);
+		LockCrossThreadMutex (GraphicsLock);
 		SetFlashRect (NULL_PTR, (FRAME)0);
-		ClearSemaphore (GraphicsSem);
+		UnlockCrossThreadMutex (GraphicsLock);
 
 		return (FALSE);
 	}
@@ -282,18 +282,18 @@ LastActivity = WON_LAST_BATTLE;
 			BatchGraphics ();
 			ClearDrawable ();
 			FlushColorXForms ();
-			SetSemaphore (GraphicsSem);
+			LockCrossThreadMutex (GraphicsLock);
 			DrawStamp (&s);
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 			UnbatchGraphics ();
 
 			FlushInput ();
 			GLOBAL (CurrentActivity) &= ~CHECK_ABORT;
 			DoInput ((PVOID)&MenuState, TRUE);
 			
-			SetSemaphore (GraphicsSem);
+			LockCrossThreadMutex (GraphicsLock);
 			SetFlashRect ((PRECT)0, (FRAME)0);
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 			DestroyDrawable (ReleaseDrawable (s.frame));
 			
 			if (GLOBAL (CurrentActivity) == (ACTIVITY)~0)
diff --git a/sc2/src/sc2code/save.c b/sc2/src/sc2code/save.c
index 490bde5a8..ac69a55a4 100644
--- a/sc2/src/sc2code/save.c
+++ b/sc2/src/sc2code/save.c
@@ -209,11 +209,11 @@ SaveProblem (void)
 	STAMP s;
 	CONTEXT OldContext;
 	
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 	OldContext = SetContext (SpaceContext);
 	SaveProblemMessage (&s);
 	FlushGraphics ();
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 
 	while (AnyButtonPress (FALSE));
 	do
@@ -223,13 +223,13 @@ SaveProblem (void)
 	} while (!(CurrentMenuState.select || CurrentMenuState.special ||
 		 (GLOBAL (CurrentActivity) & CHECK_ABORT)));
 
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 	BatchGraphics ();
 	DrawStamp (&s);
 	UnbatchGraphics ();
 	SetContext (OldContext);
 	DestroyDrawable (ReleaseDrawable (s.frame));
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 	
 	return;
 }
diff --git a/sc2/src/sc2code/setup.c b/sc2/src/sc2code/setup.c
index 6f8dc73a6..9cf0a9cf6 100644
--- a/sc2/src/sc2code/setup.c
+++ b/sc2/src/sc2code/setup.c
@@ -47,7 +47,7 @@ FONT StarConFont, MicroFont, TinyFont;
 QUEUE race_q[NUM_PLAYERS];
 SOUND MenuSounds, GameSounds;
 FRAME ActivityFrame, status, flagship_status, misc_data;
-Semaphore GraphicsSem;
+CrossThreadMutex GraphicsLock;
 CondVar RenderingCond;
 STRING GameStrings;
 
diff --git a/sc2/src/sc2code/ship.c b/sc2/src/sc2code/ship.c
index 8babd7e7e..9df5f2b7e 100644
--- a/sc2/src/sc2code/ship.c
+++ b/sc2/src/sc2code/ship.c
@@ -200,10 +200,10 @@ ship_preprocess (PELEMENT ElementPtr)
 			InitIntersectStartPoint (ElementPtr);
 			InitIntersectEndPoint (ElementPtr);
 
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 			ResumeGameClock ();
 			SetGameClockRate (HYPERSPACE_CLOCK_RATE);
-			SetSemaphore (GraphicsSem);
+			LockCrossThreadMutex (GraphicsLock);
 
 			if (hyper_transition (ElementPtr))
 				return;
diff --git a/sc2/src/sc2code/shipyard.c b/sc2/src/sc2code/shipyard.c
index 44a4daa44..c3798a3ae 100644
--- a/sc2/src/sc2code/shipyard.c
+++ b/sc2/src/sc2code/shipyard.c
@@ -92,7 +92,7 @@ int hangar_anim_func (void* data)
 		CONTEXT OldContext;
 		RECT OldClipRect;
 
-		SetSemaphore (GraphicsSem);
+		LockCrossThreadMutex (GraphicsLock);
 		OldContext = SetContext (ScreenContext);
 		GetContextClipRect (&OldClipRect);
 		SetContextClipRect (&ClipRect);
@@ -103,7 +103,7 @@ int hangar_anim_func (void* data)
 		
 		SetContextClipRect (&OldClipRect);
 		SetContext (OldContext);
-		ClearSemaphore (GraphicsSem);
+		UnlockCrossThreadMutex (GraphicsLock);
 		
 		SleepThreadUntil (TimeIn + ONE_SECOND / HANGAR_ANIM_RATE);
 		TimeIn = GetTimeCounter ();
@@ -207,7 +207,7 @@ DrawRaceStrings (BYTE NewRaceItem)
 	STAMP s;
 	CONTEXT OldContext;
 	
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 
 	OldContext = SetContext (StatusContext);
 	GetContextClipRect (&r);
@@ -272,7 +272,7 @@ DrawRaceStrings (BYTE NewRaceItem)
 	}
 	//SetFlashRect ((PRECT)~0L, (FRAME)0);
 	SetContext (OldContext);
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 }
 
 #define SHIP_WIN_WIDTH 34
@@ -497,7 +497,7 @@ ShowCombatShip (COUNT which_window, SHIP_FRAGMENTPTR YankedStarShipPtr)
 				while (AnyButtonPress (FALSE))
 					TaskSwitch();
 			}
-			SetSemaphore (GraphicsSem);
+			LockCrossThreadMutex (GraphicsLock);
 			OldContext = SetContext (OffScreenContext);
 			SetContextFGFrame (Screen);
 			SetContextBackGroundColor (BLACK_COLOR);
@@ -541,7 +541,7 @@ ShowCombatShip (COUNT which_window, SHIP_FRAGMENTPTR YankedStarShipPtr)
 			UnbatchGraphics ();
 			SetContextClipRect (NULL_PTR);
 			SetContext (OldContext);
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 		}
 	}
 }
@@ -571,9 +571,9 @@ CrewTransaction (SIZE crew_delta)
 			{
 				GLOBAL (CrewCost) += 2;
 
-				ClearSemaphore (GraphicsSem);
+				UnlockCrossThreadMutex (GraphicsLock);
 				DrawMenuStateStrings (PM_CREW, SHIPYARD_CREW);
-				SetSemaphore (GraphicsSem);
+				LockCrossThreadMutex (GraphicsLock);
 			}
 		}
 		else
@@ -583,9 +583,9 @@ CrewTransaction (SIZE crew_delta)
 			{
 				GLOBAL (CrewCost) -= 2;
 
-				ClearSemaphore (GraphicsSem);
+				UnlockCrossThreadMutex (GraphicsLock);
 				DrawMenuStateStrings (PM_CREW, SHIPYARD_CREW);
-				SetSemaphore (GraphicsSem);
+				LockCrossThreadMutex (GraphicsLock);
 			}
 		}
 		if (!(ActivateStarShip (
@@ -634,7 +634,7 @@ DoModifyShips (PMENU_STATE pMS)
 		pMS->CurState = MAKE_BYTE (0, 0xF);
 		pMS->delta_item = 0;
 
-		SetSemaphore (GraphicsSem);
+		LockCrossThreadMutex (GraphicsLock);
 		SetContext (SpaceContext);
 		goto ChangeFlashRect;
 	}
@@ -710,7 +710,7 @@ DoModifyShips (PMENU_STATE pMS)
 						);
 			}
 
-			SetSemaphore (GraphicsSem);
+			LockCrossThreadMutex (GraphicsLock);
 
 #ifdef WANT_SHIP_SPINS
 			if (special)
@@ -745,7 +745,7 @@ DoModifyShips (PMENU_STATE pMS)
 					COUNT Index;
 
 // SetFlashRect (NULL_PTR, (FRAME)0);
-					ClearSemaphore (GraphicsSem);
+					UnlockCrossThreadMutex (GraphicsLock);
 					if (!(pMS->delta_item & MODIFY_CREW_FLAG))
 					{
 						pMS->delta_item = MODIFY_CREW_FLAG;
@@ -771,12 +771,12 @@ DoModifyShips (PMENU_STATE pMS)
 						{
 							ShowCombatShip ((COUNT)pMS->CurState, (SHIP_FRAGMENTPTR)0);
 							//Reset flash rectangle
-							SetSemaphore (GraphicsSem);
+							LockCrossThreadMutex (GraphicsLock);
 							SetFlashRect ((PRECT)~0L, (FRAME)0);
-							ClearSemaphore (GraphicsSem);
+							UnlockCrossThreadMutex (GraphicsLock);
 							DrawMenuStateStrings (PM_CREW, SHIPYARD_CREW);
 
-							SetSemaphore (GraphicsSem);
+							LockCrossThreadMutex (GraphicsLock);
 							DeltaSISGauges (UNDEFINED_DELTA, UNDEFINED_DELTA,
 									-((int)ShipCost[Index]));
 							r.corner.x = pMS->flash_rect0.corner.x;
@@ -786,7 +786,7 @@ DoModifyShips (PMENU_STATE pMS)
 							r.extent.height = 5;
 							SetContext (SpaceContext);
 							SetFlashRect (&r, (FRAME)0);
-							ClearSemaphore (GraphicsSem);
+							UnlockCrossThreadMutex (GraphicsLock);
 						}
 							
 						return (TRUE);
@@ -814,7 +814,7 @@ DoModifyShips (PMENU_STATE pMS)
 						
 						return (TRUE);
 					}
-					SetSemaphore (GraphicsSem);
+					LockCrossThreadMutex (GraphicsLock);
 					goto ChangeFlashRect;
 				}
 				else if (select || cancel)
@@ -824,9 +824,9 @@ DoModifyShips (PMENU_STATE pMS)
 							&& StarShipPtr->ShipInfo.crew_level == 0)
 					{
 						SetFlashRect (NULL_PTR, (FRAME)0);
-						ClearSemaphore (GraphicsSem);
+						UnlockCrossThreadMutex (GraphicsLock);
 						ShowCombatShip ((COUNT)pMS->CurState, StarShipPtr);
-						SetSemaphore (GraphicsSem);
+						LockCrossThreadMutex (GraphicsLock);
 						UnlockStarShip (&GLOBAL (built_ship_q), hStarShip);
 						RemoveQueue (&GLOBAL (built_ship_q), hStarShip);
 						FreeStarShip (&GLOBAL (built_ship_q), hStarShip);
@@ -998,13 +998,13 @@ DoModifyShips (PMENU_STATE pMS)
 			}
 			else if (cancel)
 			{
-				ClearSemaphore (GraphicsSem);
+				UnlockCrossThreadMutex (GraphicsLock);
 
 				pMS->InputFunc = DoShipyard;
 				DrawMenuStateStrings (PM_CREW, pMS->CurState = SHIPYARD_CREW);
-				SetSemaphore (GraphicsSem);
+				LockCrossThreadMutex (GraphicsLock);
 				SetFlashRect ((PRECT)~0L, (FRAME)0);
-				ClearSemaphore (GraphicsSem);
+				UnlockCrossThreadMutex (GraphicsLock);
 
 				return (TRUE);
 			}
@@ -1031,7 +1031,7 @@ ChangeFlashRect:
 				}
 				SetFlashRect (&pMS->flash_rect0, (FRAME)0);
 			}
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 		}
 	}
 
@@ -1044,7 +1044,7 @@ DrawBluePrint (PMENU_STATE pMS)
 	COUNT num_frames;
 	STAMP s;
 
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 	SetContext (SpaceContext);
 
 	pMS->ModuleFrame = CaptureDrawable (
@@ -1155,7 +1155,7 @@ DrawBluePrint (PMENU_STATE pMS)
 	DestroyDrawable (ReleaseDrawable (pMS->ModuleFrame));
 	pMS->ModuleFrame = 0;
 
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 }
 
 void
@@ -1220,16 +1220,16 @@ DoShipyard (PMENU_STATE pMS)
 			BatchGraphics ();
 
 			DrawSISFrame ();
-			SetSemaphore (GraphicsSem);
+			LockCrossThreadMutex (GraphicsLock);
 			DrawSISMessage (GAME_STRING (STARBASE_STRING_BASE + 3));
 			DrawSISTitle (GAME_STRING (STARBASE_STRING_BASE));
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 			DrawBluePrint (pMS);
 			pMS->ModuleFrame = s.frame;
 
 			DrawMenuStateStrings (PM_CREW, pMS->CurState = SHIPYARD_CREW);
 
-			SetSemaphore (GraphicsSem);
+			LockCrossThreadMutex (GraphicsLock);
 			SetContext (SpaceContext);
 			s.origin.x = s.origin.y = 0;
 #ifdef USE_3DO_HANGAR
@@ -1261,12 +1261,12 @@ DoShipyard (PMENU_STATE pMS)
 			PlayMusic (pMS->hMusic, TRUE, 1);
 			UnbatchGraphics ();
 			BeginHangarAnim (pMS);
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 
 			ShowCombatShip ((COUNT)~0, (SHIP_FRAGMENTPTR)0);
-			SetSemaphore (GraphicsSem);
+			LockCrossThreadMutex (GraphicsLock);
 			SetFlashRect ((PRECT)~0L, (FRAME)0);
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 		}
 
 		pMS->Initialized = TRUE;
@@ -1275,13 +1275,13 @@ DoShipyard (PMENU_STATE pMS)
 	{
 ExitShipyard:
 		EndHangarAnim (pMS);
-		SetSemaphore (GraphicsSem);
+		LockCrossThreadMutex (GraphicsLock);
 		DestroyDrawable (ReleaseDrawable (pMS->ModuleFrame));
 		pMS->ModuleFrame = 0;
 		pMS->CurFrame = 0;
 		DestroyColorMap (ReleaseColorMap (pMS->CurString));
 		pMS->CurString = 0;
-		ClearSemaphore (GraphicsSem);
+		UnlockCrossThreadMutex (GraphicsLock);
 
 		return (FALSE);
 	}
@@ -1298,10 +1298,10 @@ ExitShipyard:
 			if (GameOptions () == 0)
 				goto ExitShipyard;
 			DrawMenuStateStrings (PM_CREW, pMS->CurState);
-			SetSemaphore (GraphicsSem);
+			LockCrossThreadMutex (GraphicsLock);
 			SetFlashRect ((PRECT)~0L, (FRAME)0);
 			BeginHangarAnim (pMS);
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 		}
 	}
 	else
diff --git a/sc2/src/sc2code/sis.c b/sc2/src/sc2code/sis.c
index f5c361150..bd61eabe0 100644
--- a/sc2/src/sc2code/sis.c
+++ b/sc2/src/sc2code/sis.c
@@ -73,9 +73,9 @@ ClearSISRect (BYTE ClearFlags)
 
 	if (ClearFlags & CLEAR_SIS_RADAR)
 	{
-		ClearSemaphore (GraphicsSem);
+		UnlockCrossThreadMutex (GraphicsLock);
 		DrawMenuStateStrings ((BYTE)~0, 1);
-		SetSemaphore (GraphicsSem);
+		LockCrossThreadMutex (GraphicsLock);
 #ifdef NEVER
 		r.corner.x = RADAR_X - 1;
 		r.corner.y = RADAR_Y - 1;
@@ -812,7 +812,7 @@ DeltaSISGauges (SIZE crew_delta, SIZE fuel_delta, int resunit_delta)
 				SUPPORT_SHIP_PTS
 			};
 
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 			for (hStarShip = GetHeadLink (&GLOBAL (built_ship_q)),
 					pship_pos = ship_pos;
 					hStarShip; hStarShip = hNextShip, ++pship_pos)
@@ -828,16 +828,16 @@ DeltaSISGauges (SIZE crew_delta, SIZE fuel_delta, int resunit_delta)
 				s.origin.x = pship_pos->x;
 				s.origin.y = pship_pos->y;
 				s.frame = StarShipPtr->ShipInfo.icons;
-				SetSemaphore (GraphicsSem);
+				LockCrossThreadMutex (GraphicsLock);
 				DrawStamp (&s);
-				ClearSemaphore (GraphicsSem);
+				UnlockCrossThreadMutex (GraphicsLock);
 
 				UnlockStarShip (
 						&GLOBAL (built_ship_q),
 						hStarShip
 						);
 			}
-			SetSemaphore (GraphicsSem);
+			LockCrossThreadMutex (GraphicsLock);
 		}
 	}
 
@@ -1313,7 +1313,7 @@ int flash_rect_func(void *data)
 								&tmp_rect, strength, 4);
 				}
 			}
-			SetSemaphore (GraphicsSem);
+			LockCrossThreadMutex (GraphicsLock);
 			OldContext = SetContext (ScreenContext);
 			SetContextClipRect (&cached_rect);
 			// flash changed_can't be modified while GraphicSem is held
@@ -1321,7 +1321,7 @@ int flash_rect_func(void *data)
 				DrawStamp (pStamp);
 			SetContextClipRect (NULL_PTR); // this will flush whatever
 			SetContext (OldContext);
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 		}
 		FlushGraphics ();
 		SleepThreadUntil (TimeIn + WaitTime);
@@ -1391,9 +1391,9 @@ SetFlashRect (PRECT pRect, FRAME f)
 		flash_rect1.extent.width = 0;
 		if (flash_task)
 		{
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 			ConcludeTask (flash_task);
-			SetSemaphore (GraphicsSem);
+			LockCrossThreadMutex (GraphicsLock);
 		}
 	}
 	else
diff --git a/sc2/src/sc2code/starbase.c b/sc2/src/sc2code/starbase.c
index b10453cc0..8db7ecfd7 100644
--- a/sc2/src/sc2code/starbase.c
+++ b/sc2/src/sc2code/starbase.c
@@ -256,12 +256,12 @@ s.origin.x = SAFE_X, s.origin.y = SAFE_Y + 4;
 	{
 		//CONTEXT OldContext;
 		
-		SetSemaphore (GraphicsSem);
+		LockCrossThreadMutex (GraphicsLock);
 		DrawStamp (&s);
 		s.frame = IncFrameIndex (s.frame);
 		if (s.frame == pMenuState->CurFrame)
 			s.frame = IncFrameIndex (s.frame);
-		ClearSemaphore (GraphicsSem);
+		UnlockCrossThreadMutex (GraphicsLock);
 		
 		SleepThreadUntil (TimeIn + (ONE_SECOND / 20));
 		TimeIn = GetTimeCounter ();
@@ -287,7 +287,7 @@ DoStarBase (PMENU_STATE pMS)
 		LastActivity &= ~CHECK_LOAD;
 		pMS->InputFunc = DoStarBase;
 
-		SetSemaphore (GraphicsSem);
+		LockCrossThreadMutex (GraphicsLock);
 		SetFlashRect (NULL_PTR, (FRAME)0);
 
 		if (pMS->hMusic)
@@ -306,7 +306,7 @@ DoStarBase (PMENU_STATE pMS)
 		pMS->Initialized = TRUE;
 		SetContext (ScreenContext);
 
-		ClearSemaphore (GraphicsSem);
+		UnlockCrossThreadMutex (GraphicsLock);
 
 		s.origin.x = s.origin.y = 0;
 s.origin.x = SAFE_X, s.origin.y = SAFE_Y + 4;
@@ -314,7 +314,7 @@ s.origin.x = SAFE_X, s.origin.y = SAFE_Y + 4;
 		pMS->CurFrame = s.frame;
 		pMS->hMusic = LoadMusicInstance (STARBASE_MUSIC);
 
-		SetSemaphore (GraphicsSem);
+		LockCrossThreadMutex (GraphicsLock);
 		SetTransitionSource (NULL);
 		BatchGraphics ();
 		SetContextBackGroundColor (BLACK_COLOR);
@@ -334,7 +334,7 @@ s.origin.x = SAFE_X, s.origin.y = SAFE_Y + 4;
 		UnbatchGraphics ();
 		pMS->flash_task = AssignTask (rotate_starbase, 4096,
 				"rotate starbase");
-		ClearSemaphore (GraphicsSem);
+		UnlockCrossThreadMutex (GraphicsLock);
 	}
 	else if (CurrentMenuState.select
 			|| GET_GAME_STATE (MOONBASE_ON_SHIP)
@@ -410,9 +410,9 @@ ExitStarBase:
 
 		if (NewState != pMS->CurState)
 		{
-			SetSemaphore (GraphicsSem);
+			LockCrossThreadMutex (GraphicsLock);
 			DrawBaseStateStrings (pMS->CurState, NewState);
-			ClearSemaphore (GraphicsSem);
+			UnlockCrossThreadMutex (GraphicsLock);
 			pMS->CurState = NewState;
 		}
 	}
diff --git a/sc2/src/sc2code/starcon.c b/sc2/src/sc2code/starcon.c
index e9d4e4081..161b7f73e 100644
--- a/sc2/src/sc2code/starcon.c
+++ b/sc2/src/sc2code/starcon.c
@@ -46,7 +46,7 @@ int arilou_gate_task(void* data)
 	counter = GET_GAME_STATE (ARILOU_SPACE_COUNTER);
 	while (!Task_ReadState (task, TASK_EXIT))
 	{
-		SetSemaphore (GLOBAL (GameClock.clock_sem));
+		LockCrossThreadMutex (GLOBAL (GameClock.clock_lock));
 
 		if (GET_GAME_STATE (ARILOU_SPACE) == OPENING)
 		{
@@ -59,11 +59,11 @@ int arilou_gate_task(void* data)
 				counter = 0;
 		}
 
-		SetSemaphore (GraphicsSem);
+		LockCrossThreadMutex (GraphicsLock);
 		SET_GAME_STATE (ARILOU_SPACE_COUNTER, counter);
-		ClearSemaphore (GraphicsSem);
+		UnlockCrossThreadMutex (GraphicsLock);
 
-		ClearSemaphore (GLOBAL (GameClock.clock_sem));
+		UnlockCrossThreadMutex (GLOBAL (GameClock.clock_lock));
 		SleepThreadUntil (TimeIn + BATTLE_FRAME_RATE);
 		TimeIn = GetTimeCounter ();
 	}
@@ -980,9 +980,9 @@ sc = _simple_count;
 							(int)_simple_count - (int)sc);
 #endif //TESTING
 
-				SetSemaphore (GraphicsSem);
+				LockCrossThreadMutex (GraphicsLock);
 				SetFlashRect (NULL_PTR, (FRAME)0);
-				ClearSemaphore (GraphicsSem);
+				UnlockCrossThreadMutex (GraphicsLock);
 
 				LastActivity = GLOBAL (CurrentActivity);
 
diff --git a/sc2/src/sc2code/starcon.h b/sc2/src/sc2code/starcon.h
index c1ffa1622..a652acd0e 100644
--- a/sc2/src/sc2code/starcon.h
+++ b/sc2/src/sc2code/starcon.h
@@ -163,7 +163,7 @@ extern BOOLEAN PagingEnabled;
 extern FRAME ActivityFrame;
 extern SOUND MenuSounds, GameSounds;
 extern QUEUE race_q[NUM_PLAYERS];
-extern Semaphore GraphicsSem;
+extern CrossThreadMutex GraphicsLock;
 extern CondVar RenderingCond;
 extern STRING GameStrings;
 
diff --git a/sc2/src/sc2code/utils.c b/sc2/src/sc2code/utils.c
index 72a32af65..1cecf5f79 100644
--- a/sc2/src/sc2code/utils.c
+++ b/sc2/src/sc2code/utils.c
@@ -159,7 +159,7 @@ PauseGame (void)
 	if (CommData.ConversationPhrases && PlayingTrack ())
 		PauseTrack ();
 
-	SetSemaphore (GraphicsSem);
+	LockCrossThreadMutex (GraphicsLock);
 	OldContext = SetContext (ScreenContext);
 	OldHot = SetFrameHot (Screen, MAKE_HOT_SPOT (0, 0));
 
@@ -171,12 +171,12 @@ PauseGame (void)
 	F = CaptureDrawable (LoadDisplayPixmap (&r, (FRAME)0));
 	DrawStamp (&s);
 
-	// Releasing the Semaphore lets the rotate_planet_task
+	// Releasing the lock lets the rotate_planet_task
 	// draw a frame.  PauseRotate can still allow one more frame
-	// to be drawn, so it is safer to just not release the Semaphore
-	//ClearSemaphore (GraphicsSem);
+	// to be drawn, so it is safer to just not release the lock
+	//UnlockCrossThreadMutex (GraphicsLock);
 	FlushGraphics ();
-	//SetSemaphore (GraphicsSem);
+	//LockCrossThreadMutex (GraphicsLock);
 
 	while (ImmediateInputState.pause)
 		TaskSwitch ();
@@ -208,7 +208,7 @@ PauseGame (void)
 			do_subtitles ((void *)~0);
 	}
 
-	ClearSemaphore (GraphicsSem);
+	UnlockCrossThreadMutex (GraphicsLock);
 
 	TaskSwitch ();
 	GLOBAL (CurrentActivity) &= ~CHECK_PAUSE;
diff --git a/sc2/src/starcon2.c b/sc2/src/starcon2.c
index 511f4c399..e9f01c27e 100644
--- a/sc2/src/starcon2.c
+++ b/sc2/src/starcon2.c
@@ -348,7 +348,7 @@ main (int argc, char *argv[])
 	InitTimeSystem ();
 	InitTaskSystem ();
 
-	GraphicsSem = CreateSemaphore (1, "Graphics");
+	GraphicsLock = CreateCrossThreadMutex ("Graphics");
 	RenderingCond = CreateCondVar ();
 
 	TFB_InitGraphics (gfxdriver, gfxflags, width, height, bpp);