patch 8.2.1027: GUI: multi-byte characters do not work in a terminal

Problem:    GUI: multi-byte characters do not work in a terminal.
Solution:   Do not assume a key is one byte. (closes #6304)

src/gui_gtk_x11.c

@@ -1215,7 +1215,10 @@ key_press_event(GtkWidget *widget UNUSED,
     if (len == -3)
 	key = TO_SPECIAL(string[1], string[2]);
     else
-	key = string[0];
+    {
+	string[len] = NUL;
+	key = mb_ptr2char(string);
+    }
 
     // Handle modifiers.
     modifiers = modifiers_gdk2vim(state);
@@ -1240,8 +1243,7 @@ key_press_event(GtkWidget *widget UNUSED,
 	// May remove the shift modifier if it's included in the key.
 	modifiers = may_remove_shift_modifier(modifiers, key);
 
-	string[0] = key;
-	len = 1;
+	len = mb_char2bytes(key, string);
     }
 
     if (modifiers != 0)

src/gui_x11.c

@@ -938,7 +938,10 @@ gui_x11_key_hit_cb(
     if (len == -3)
 	key = TO_SPECIAL(string[1], string[2]);
     else
-	key = string[0];
+    {
+	string[len] = NUL;
+	key = mb_ptr2char(string);
+    }
     key = simplify_key(key, &modifiers);
     if (key == CSI)
 	key = K_CSI;
@@ -951,8 +954,7 @@ gui_x11_key_hit_cb(
     }
     else
     {
-	string[0] = key;
-	len = 1;
+	len = mb_char2bytes(key, string);
 
 	// Remove the SHIFT modifier for keys where it's already included,
 	// e.g., '(', '!' and '*'.

src/version.c

@@ -754,6 +754,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1027,
 /**/
     1026,
 /**/