[PATCH 0/1] MR6482: win32u: Leave window surface alpha bits to -1 when unset.

[Rémi Bernon]

Fixes: 05d727a935b9009f188cc74ca77e14afc44aef30
Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=57160

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https://gitlab.winehq.org/wine/wine/-/merge_requests/6482