I use a listbox inside a bandpopup with the following code:

<bandbox id="shiftGroupManagerBandBox"
readonly="true"
mold="rounded"
>
<bandpopup hflex="min">
<listbox id="shiftGroupManagerListBox"
multiple="true"
checkmark="true"
rows="0"
hflex="min"
/>
</bandpopup>
</bandbox>

The first time I fill listitems with java:

@Override
public void doAfterCompose(Component comp) throws Exception {
super.doAfterCompose(comp);
...
...
shiftGroupManagerList = shiftGroupManagerService.findAllShiftGroupManager();
for (ShiftGroupManager shiftGroupManagerEntry : shiftGroupManagerList)

{ Listitem li = new Listitem(); li.setValue(shiftGroupManagerEntry.getShiftGroupManagerId().toString()); li.setLabel(shiftGroupManagerEntry.getShiftGroupManagerLastName()); shiftGroupManagerListBox.appendChild(li); }

...
...
}

bandpopup define its width correctly.
But if i remove all shiftGroupManagerListBox children with:

shiftGroupManagerListBox.getChildren().clear();

and then if I fill again shiftGroupManagerListBox with different listitems, a horizontal scrollbar appears on bandpopup, maybe because one or more new listitems are wider than the ones I cleared before.
It seems like bandpopup width be setup only the first time but then no.