bandbox popup not aligned correctly on FF10/IE9

Example:
<vbox>
<bandbox id="bd" mold="rounded" style="padding-left: 250px">
<bandpopup>
<vbox>
<hbox>
Search
<textbox />
</hbox>
<listbox
onSelect="bd.value=self.selectedItem.label; bd.close();">
<listhead>
<listheader label="Name" />
<listheader label="Description" />
</listhead>
<listitem>
<listcell label="John" />
<listcell label="CEO" />
</listitem>
<listitem>
<listcell label="Joe" />
<listcell label="Engineer" />
</listitem>
<listitem>
<listcell label="Mary" />
<listcell label="Supervisor" />
</listitem>
</listbox>
</vbox>
</bandpopup>
</bandbox>
</vbox>
Expected: On FF10/IE9, the bandbox popup should align with bandbox input box's left edge.
Actual: Very first time when the popup is opened the popup is at the left edge of the window instead of left edge of bandbox inputbox. Subsequent popup display correctly aligns with left edge of bandbox input box.