Multiple field fly-out value list?

[Rich S]

I think I saw this somewhere as a plug-in, but I may be mistaken:

What I want to do is have the ability to select from three separate value lists to pop a value into a text field. For example, there's one value list for Building, one for Room Name and one for Room Number. What I'd like to do is click on a text field to pull up the value list for Building; When I select a building from the list then a fly-out value list for Room Name would appear; I'd draw over to Room Name, select a value, then a fly-out value list would appear for Room Number to select a room number. When I unclick the mouse, those three values would populate the field.

Is there such a plug-in/calc/function, or have I been drinking too much coffee again? TIA for your replies!