After the change to move the sync_gl_drawable call outside the win_data mutex in 54d82ed4, the X11 client rect used for determining whether we need to composite/clip the drawable can be out of sync with the win32 side. This would result in offscreening when unnecessary and vice-versa.
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v3: winex11: Use the win32 client rect in needs_client_window_clipping.
https://gitlab.winehq.org/wine/wine/-/merge_requests/7106