a listbox() or a v/hlistbox()?
if it's a listbox() you can just listbox << Get Items.
If it's a vlistbox and you're using Jmp 13 you can do nitems(vlistbox) and loop through them.
if you're using jmp12- you have to do something like
Names Default to here(1);
new window("Test",
vlb = vlistbox(
textbox("1"),
textbox("1"),
textbox("1"),
textbox("1"),
textbox("1"),
textbox("1"),
textbox("1"),
textbox("1"),
)
);
l = {};
for(box = vlb<<child, !isempty(box), box = box << Sib,
insert into(l, box)
);