Was wondering if it would be possible to create a toggle costume hotkey so on release of a button or keypress it goes back to the previously equipped costume.  Trying to make an "idle" and "drawing" state using the mouse click key.  Maybe the user could define what costume hotkey it goes back to or just previous used costume.  

I think an even better idea could be expanding the hotkeys in general to make them fully customizable instead of just the number row.  If you could map any key/combo/button to a costume, then you could potentially get your idea as a side-effect of the feature.

It could be drilled down even further to have the ability to set to key_down and key_up for different things.