Hello,
I am running Ubuntu MATE 18.04, and am unable to change the theme for Mate Window Applets - Window Buttons.
I am attempting to change the theme of Mate Window Applets - Window Buttons from Ambiant-MATE to Arc-Darker. Every time I attempt to change the theme, after relaunching mate-panel, any theme other than Ambiant-MATE causes Mate Window Applets - Window Buttons to default back to out of place, pure black buttons that look like they have been scaled up.
This does in no way a game breaking bug, nor something that inhibits my ability to use UM, but I do find it to be a rather annoying paper cut.
Cheers