time transition not on artboards?

I've read elsewhere that time transitions are only available for artboards which I find very strange. How do you prototype the "down" state of a button?  The down state should only flash briefly when a click is completed or remain displayed while the button is clicked. There's no "hover out" or timing trigger so unless I build an overcomplicated and unusable thing using overlays I can't find a way to do this BASIC thing!