Hi, Dinya,
Not 100% sure I got the question, but just trying...
I think you can populate a listbox on application start-up with whatever the values you want to be populated there and enable single/multiple selection to suit your (users) taste. A sample sentence would be:
LISTBOX_COUNTRIES_1.setItems(DS_1.getMemberList("0COUNTRY", MemberPresentation.INTERNAL_KEY, MemberDisplay.KEY, 99, 'All Members'));
you can also read more on this function in the CTRL+SPACE while typing this sentence in DesignStudio...