Replace custom star widget with GTKToggleButton
The custom implementation wasn't necessary. Using native widgets makes the UI more consistent and predictable.
I wrote this patch because I would accidentally play the song instead of favoriting it because the icon was small and there was no hover visual feedback.
Before:
After:
Changes:
- Uses the favorite icon
- Hover effect
- Changed color to white (up for discussion)
It would be interesting to have a star widget in LibAdvaita or some other shared library, as many Gnome apps have something similar.