Win32SS drawing glitch when rapps is updating the DB

Reproduction steps

• just start rapps and make it update its database

Expected result
the background window should never overpaint the foreground window
(I am not totally sure, whether its the foreground window that should disappear sooner or whether it's the overpainting that should be prevented)

Observed result
The background windows border paints over the window with the progress bar.
0.4.13-RC-37-ge0475c6.webm

The only thing that gets logged in this scenario is

(win32ss/user/ntuser/msgqueue.c:1267) err: MsqSendMessage timed out 2 Status 102