prevent crashes when unexpectedly forced to exit fullscreen mode

(e.g. using windows keys in fullscreen)


Imported-from: https://svn.code.sf.net/p/dosbox/code-0/dosbox/trunk@2251

include/vga.h

@@ -345,6 +345,7 @@ void VGA_SetBlinking(Bitu enabled);
 void VGA_SetCGA2Table(Bit8u val0,Bit8u val1);
 void VGA_SetCGA4Table(Bit8u val0,Bit8u val1,Bit8u val2,Bit8u val3);
 void VGA_ActivateHardwareCursor(void);
+void VGA_KillDrawing(void);
 
 extern VGA_Type vga;
 

src/gui/sdlmain.cpp

@@ -16,7 +16,7 @@
  *  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  */
 
-/* $Id: sdlmain.cpp,v 1.86 2005-07-19 19:45:32 qbix79 Exp $ */
+/* $Id: sdlmain.cpp,v 1.87 2005-07-28 19:53:42 c2woody Exp $ */
 
 #ifndef _GNU_SOURCE
 #define _GNU_SOURCE
@@ -40,6 +40,7 @@
 #include "support.h"
 #include "debug.h"
 #include "mapper.h"
+#include "vga.h"
 
 //#define DISABLE_JOYSTICK
 
@@ -979,8 +980,16 @@ void GFX_Events() {
 						CaptureMouse();	
 					SetPriority(sdl.priority.focus);
 				} else {
-					if (sdl.mouse.locked) 
-						CaptureMouse();	
+					if (sdl.mouse.locked) {
+#ifdef WIN32
+						if (sdl.desktop.fullscreen) {
+							VGA_KillDrawing();
+							sdl.desktop.fullscreen=false;
+							GFX_ResetScreen();
+						}
+#endif
+						CaptureMouse();
+					}
 					SetPriority(sdl.priority.nofocus);
 				}
 			}

src/hardware/vga_draw.cpp

@@ -523,3 +523,7 @@ void VGA_SetupDrawing(Bitu val) {
 		PIC_AddEvent(VGA_VerticalTimer,vga.draw.delay.vtotal);
 	}
 };
+
+void VGA_KillDrawing(void) {
+	PIC_RemoveEvents(VGA_DrawPart);
+}