comctl32: Ensure that trackbar respond only to changes in WM_CAPTURECHANGED handler.

Signed-off-by: Christopher Thielen <cthielen@gmail.com>
Signed-off-by: Alexandre Julliard <julliard@winehq.org>

dlls/comctl32/trackbar.c

@@ -1979,6 +1979,7 @@ TRACKBAR_WindowProc (HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
 
 
     case WM_CAPTURECHANGED:
+        if (hwnd == (HWND)lParam) return 0;
         return TRACKBAR_CaptureChanged (infoPtr);
 
     case WM_CREATE: