[Bug 52515] Resizing/maximizing foobar2000 has stale rendering errors (more in Light Blue theme)

[WineHQ Bugzilla]

https://bugs.winehq.org/show_bug.cgi?id=52515

--- Comment #2 from Zhiyi Zhang <zzhang at codeweavers.com> ---
Created attachment 71862
  --> https://bugs.winehq.org/attachment.cgi?id=71862
test program

I spent several days looking at this bug but haven't been able to figure out
why on Windows this doesn't appear. I can reproduce this problem with control
spy v6 as well.
So I use it to debug since the bug behavior with foobar2000 is less visible
comparatively. When enlarging control spy horizontally, there is a good chance
the "Extended styles" list box horizontal scrollbar overlaps the buttons on its
right, e.g., Apply, Recreate and Reset buttons. The reason why this would
happen on Wine is something like this. When the application receives size
change messages, MoveWindow(listbox_handle, positions..., TRUE) and
MoveWindow(button_handle, positions..., TRUE) is called. When the list box
paints the scrollbar, it paints into the original window rectangle that the
buttons were in, so their window content is corrupted. Then,
MoveWindow(button_handle, positions..., TRUE) will use
move_window_bits_parent() to move the corrupted content to the new window
rectangle. The problem is, on Windows, right after WM_WINDOWPOSCHANGING
messages, WINDOWPOS.flags get added a SWP_NOCOPYBITS bit on Windows. This bit
is not from the application, so it's from SetWindowPos() internally. And I
haven't been able to figure out the condition that Windows automatically add
this bit. It seems to be some kind of live resize heuristics. I also try to
reproduce the same behavior using a sample program. However, the bug can be
reproduced on Windows as well with the sample program so it's not helpful.
Running out of ideas, I have to give this up for the moment.

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