I am uncertain if this question has been raised before, but I've been unable to find anything on the topic. I have been using BBT for a while now, but I miss the ability for a button to change appearance when pressed, suitable for the mute function for instance, like Apple's default control strip-button that removes the sound waves when muted, or like the volume control where the volume level is depicted by the number of sound-waves lit.
I don't know if this function exists, or if it has been suggested, but maybe someone can enlighten me?