Added logic to now pass ALT + Return to the SDL event queue as the is fullscreen toggle that is handled by GTK.

src/drivers/sdl/gui.cpp

@@ -2434,6 +2434,17 @@ static gboolean convertKeypress (GtkWidget * grab, GdkEventKey * event,
 	}
 	sdlev.key.repeat = 0;
 
+
+	if ( (event->state & GDK_MOD1_MASK) ||
+			getKeyState( SDL_SCANCODE_LALT ) || getKeyState( SDL_SCANCODE_RALT ) )
+	{
+		// Don't pass ALT + Enter to game, as this toggles fullscreen in GTK
+		if ( sdlkey == SDLK_RETURN )
+		{
+			return FALSE;
+		}
+	}
+
 	if (sdlkey != 0)
 	{
 		SDL_PushEvent (&sdlev);

src/drivers/sdl/input.cpp

@@ -147,6 +147,15 @@ static int DIPS = 0;
 static uint8 keyonce[MKK_COUNT];
 #define KEY(__a) g_keyState[MKK(__a)]
 
+int getKeyState( int k )
+{
+	if ( (k >= 0) && (k < SDL_NUM_SCANCODES) )
+	{
+		return g_keyState[k];
+	}
+	return 0;
+}
+
 static int
 _keyonly (int a)
 {

src/drivers/sdl/input.h

@@ -20,6 +20,7 @@ extern ARGPSTRUCT InputArgs[];
 extern int Hotkeys[];
 void ParseGIInput(FCEUGI *GI);
 void setHotKeys();
+int getKeyState( int k );
 int ButtonConfigBegin();
 void ButtonConfigEnd();
 void ConfigButton(char *text, ButtConfig *bc);