If data are static, and you want one column only, it is simple:

DEFINE POPUP myListBoxItems
DEFINE BAR 1 OF myListBoxItems PROMPT "Item1" COLOR RGB(100,100,100,20,20,20)
DEFINE BAR 2 OF myListBoxItems PROMPT "Item2"
DEFINE BAR 3 OF myListBoxItems PROMPT "Item3"
* ....
listboxObject.RowSourceType = 9
listboxObject.RowSource = "myListBoxItems"

otherwise you must write a loop code for build the popup.

If you redefine a bar VFP refresh the listbox row,
but the refresh is not done for all the attributes.

Fabio