I'm not sure if this thread is still catching some action, but...
I stumbled onto this technique while looking to solve another problem. I recognized the application immediately as a solve for another problem I was trying to figure out a few days earlier. Funny how that works sometimes!
How it works: When clicking on the drawer face (when it's in a cabinet) the whole drawer opens. The second click makes the top tray move back toward the cabinet revealing the bottom tray. Third click, top tray moves forward again. Fourth click, the drawer closes.
I'm not sure if the "On Click" code could be simplified and still work the same as I'm quite new to DC syntax.