The SDL3 migration guide [1] says:
> The following window operations are now considered to be asynchronous
requests and should not be assumed to succeed unless a corresponding
event has been received […]
Remove the boolean fields used to track the window state, as they were
fundamentally inconsistent with SDL's internal state. Use
SDL_GetWindowFlags() explicitly instead.
[1]: <https://wiki.libsdl.org/SDL3/README-migration>
Refs #6216 comment <https://github.com/Genymobile/scrcpy/pull/6216#discussion_r2651810005>
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