patch 9.1.0881: GUI: message dialog may not get focus

Problem:  GUI: message dialog may not get focus
Solution: add window manager hint to give focus to the dialog
          (Chris White)

Tell the window manager that message dialogs should be given focus when
the user switches from another application back to Vim.  This can
happen, e.g., when the user has a file open in Vim and then edits it
in another program.

fixes: #172
closes: #16100

Signed-off-by: Chris White <christopher.white@crowdstrike.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

src/gui_gtk.c

@@ -1790,6 +1790,8 @@ gui_mch_dialog(int	type,	    // type of dialog
     dialog = create_message_dialog(type, title, message);
     dialoginfo.dialog = GTK_DIALOG(dialog);
     dialog_add_buttons(GTK_DIALOG(dialog), buttons);
+    gtk_window_set_type_hint(GTK_WINDOW(dialog),
+			     GDK_WINDOW_TYPE_HINT_POPUP_MENU);
 
     if (textfield != NULL)
     {