Hello! I have just installed the Simple Tab Groups add-on and moved it to tab bar (using the Customize menu), but unfortunately its icon remains black since it is an add-on, so it doesn't have a gray/white variant like the the native Firefox buttons. Since I use the default theme in Firefox my tab bar is black all the time (and I need/want to keep it that way) so what I'd like to do is just recolor the Simple Tab Groups add-on icon myself. I just have no idea where the icon data is stored and how I could do so. Help is appreciated! ''-FB-Productions''