Temporarily disable DwmFlush()

For some reason this locks up the Windows compositor when called by Steam. I'm disabling it for now until we understand why and whether this can cause issues for other applications as well.

src/video/windows/SDL_windowsevents.c

@@ -1865,10 +1865,12 @@ LRESULT CALLBACK WIN_WindowProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lPara
             SDL_OnWindowLiveResizeUpdate(data->window);
 
 #if !defined(SDL_PLATFORM_XBOXONE) && !defined(SDL_PLATFORM_XBOXSERIES)
+#if 0 // This locks up the Windows compositor when called by Steam; disabling until we understand why
             // Make sure graphics operations are complete for smooth refresh
             if (data->videodata->DwmFlush) {
                 data->videodata->DwmFlush();
             }
+#endif
 #endif
             return 0;
         }