quartz/tests: Add a background brush test for video renderer.

dlls/quartz/tests/videorenderer.c

@@ -2329,6 +2329,7 @@ static void test_video_window(void)
     WNDCLASSA window_class = {0};
     struct testfilter source;
     LONG width, height, l;
+    ULONG_PTR background;
     IVideoWindow *window;
     IBaseFilter *filter;
     HWND hwnd, our_hwnd;
@@ -2366,6 +2367,9 @@ static void test_video_window(void)
     tid = GetWindowThreadProcessId(hwnd, NULL);
     ok(tid == GetCurrentThreadId(), "Expected tid %#lx, got %#lx.\n", GetCurrentThreadId(), tid);
 
+    background = GetClassLongPtrW(hwnd, GCLP_HBRBACKGROUND);
+    todo_wine ok(!background, "Expected NULL brush, got %#Ix\n", background);
+
     hr = IBaseFilter_QueryInterface(filter, &IID_IVideoWindow, (void **)&window);
     ok(hr == S_OK, "Got hr %#lx.\n", hr);