[RBG7-L] - Multiple-select listbox-like strategies?

[Bill Downall]

I have a customer who says "I like this, but please let me select a few 
of them at once.  Like in the web page!"

The web page she is referring to has an HTML <SELECT> tag that allows 
multiple selections. The R:BASE CHOOSE command with the CHKBOX option 
allows multiple selections.

I can't find an R:BASE form object (like variable list box or variable 
user-defined list box) that allows multiple selections. What strategies 
can you help me brainstorm?

Bill