ComboBox, that's the select menu. Sorry, HTML terms here.
As far as I know, it's hard coded.
However; you can play with it and see if it will work?
VI's netorious for hard coding tons of things, this even includes options that are given details to make but no possiable do to UI limitations.
The most I can say is to play with it and see what happens. If you get it working, post it! I'm sure others will be interested in your new found knowledge.