Fullscreen to windowed mode switch

From Melesie

I noticed that when user switches from fullscreen mode to windowed mode and exits application while in windowed mode, Windows performs an additional change of display settings, even though desktop resolution is the same as current one. This causes short black screen to show up. The only way I know of avoiding this is to explicitly switch to default display settings found in registry. MSDN documentation for ChangeDisplaySettingsEx states:

Passing NULL for the lpDevMode parameter and 0 for the dwFlags parameter is the easiest way to return to the default mode after a dynamic mode change.

src/video/windows/SDL_windowsmodes.c

@@ -274,9 +274,11 @@ WIN_SetDisplayMode(_THIS, SDL_VideoDisplay * display, SDL_DisplayMode * mode)
     SDL_DisplayModeData *data = (SDL_DisplayModeData *) mode->driverdata;
     LONG status;
 
-    status =
-        ChangeDisplaySettingsEx(displaydata->DeviceName, &data->DeviceMode,
-                                NULL, CDS_FULLSCREEN, NULL);
+    if (mode->driverdata == display->desktop_mode.driverdata) {
+        status = ChangeDisplaySettingsEx(displaydata->DeviceName, NULL, NULL, 0, NULL);
+    } else {
+        status = ChangeDisplaySettingsEx(displaydata->DeviceName, &data->DeviceMode, NULL, CDS_FULLSCREEN, NULL);
+    }
     if (status != DISP_CHANGE_SUCCESSFUL) {
         const char *reason = "Unknown reason";
         switch (status) {