macosx: Fix bottom control bar visual bugs
At the moment, the bottom control bar exhibits issues when switching between light/dark themes:
Screen_Recording_2022-06-23_at_01.06.00
This PR ensures that the bottom playback control bar correctly reacts to appearance changes:
Screen_Recording_2022-06-23_at_01.08.14
Signed-off-by: Claudio Cambra claudio.cambra@gmail.com