I've exhausted my ideas for using DOM manipulation to alter the state of the checkbox. See Bugzilla defect https://bugzilla.mozilla.org/show_bug.cgi?id=470341 .
Based off this Firefox defect, I believe the only way to get a combobox / menubox is to prevent JSF from rendering the size="1" attribute altogether. Theres no reason for it to be rendered in the first place.
