In the Vanilla version, we had a cyCircled plugin to allow custom styling of RingMenu buttons. I'm not aware whether cyCircled will be ported to Classic or if there is an equally popular replacement for it. If there is, we should try to support it.

If this doesn't work out, an alternative would be to provide a few hand-crafted styling presets that should be general-purpose (e.g. default square and circular button styles).

Masque and Facade were suggested here.

This also relates to display of cooldown timers by OmniCC (requested here and here).

Masque support was added by @cpulley in #27 and is available in v2.2.0.