diff -r c0689749d4b4 src/video/windows/SDL_windowsframebuffer.c
--- a/src/video/windows/SDL_windowsframebuffer.c	Sun May 17 21:23:17 2020 +0200
+++ b/src/video/windows/SDL_windowsframebuffer.c	Sun May 17 22:54:23 2020 +0200
@@ -98,9 +98,12 @@
 
 int WIN_UpdateWindowFramebuffer(_THIS, SDL_Window * window, const SDL_Rect * rects, int numrects)
 {
-    SDL_WindowData *data = (SDL_WindowData *) window->driverdata;
+    HDC hdc = ((SDL_WindowData *) window->driverdata)->hdc;
 
-    BitBlt(data->hdc, 0, 0, window->w, window->h, data->mdc, 0, 0, SRCCOPY);
+    for (i = 0; i < numrects; ++i) {
+        BitBlt(hdc, rects[i].x, rects[i].y, rects[i].w, rects[i].h,
+               mdc, rects[i].x, rects[i].y, SRCCOPY);
+    }
     return 0;
 }