This prevents a "Failed to get xinerama fullscreen monitor indices." error
when minimizing a fullscreen window.
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v2: winex11: Properly handle minimized windows in update_net_wm_fullscreen_monitors().
https://gitlab.winehq.org/wine/wine/-/merge_requests/6648
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v2: winex11: Get rid of X11DRV_XDND_HasHDROP helper.
winex11: Use a custom IEnumFORMATETC interface implementation.
winex11: Clear the XDND data object on drop event.
winex11: Get rid of X11DRV_XDND_SendDropFiles helper.
winex11: Assume that PostMessageW WM_DROPFILES succeeds.
winex11: Only enter the CS to get a reference on the data object.
https://gitlab.winehq.org/wine/wine/-/merge_requests/6682