Looks like your keydefinitions have become mixed up.
"[F]" and "Mouse Left+Double Click" are the default keys for Full screen switch in both windowed and full screen mode.
Try to restore:
(rightclick >) Options > Preferences > Key definitions & WinLIRC
Select "Full screen switch" and click on the button "[Reset to default]" (at the south-east of window)
(Do the same for Windowed and Full Screen mode).
Any result?