Remove window decorations when fullscreen
Remove window decorations when fullscreen

Fix a compatibility issue with metacity 3.36, where SDL and the WM
might keep fighting for the window flags in an endless loop and/or in
an inconsistent window mode.

Upstream reference: https://gitlab.gnome.org/GNOME/metacity/-/issues/11

libavg/libavg,libavg/libavg,libavg/libavg,libavg/libavg