James,
we are currently working on an article which explains the method for such value lists (would be too long for a forum post). Hang in there, please.
Here are some hints, so you can work it out for yourself if it’s urgent:
our labels use the ui_custom_popup_infield GDL command. It can create a “value list” using the returned array values of requests in the User Interface script alone. The selected value can be displayed in 2D.
Dominika Bobály
Product Manager
GRAPHISOFT SE