macosx: Work around unresizeable library window bug

This PR works around a bug which makes the library window un-resizeable through window-edge dragging:

Screen_Recording_2022-06-28_at_22.31.45

Prior to this PR:

Screen_Recording_2022-06-28_at_22.33.56

Signed-off-by: Claudio Cambra claudio.cambra@gmail.com