Wich is the FLTK in use for it ? is it 2.0x ? or the 1.1x one ?
EDIT: it's 1.1x...just reading about it ...sorry
I think the tabs are not free to move in the panel (fixed width), but it's not really important, just see if it can be "open" or "close" ! as we can do a sort of dynamic menu !
Creates a new Fl_Tabs widget using the given position, size, and label string. The default boxtype is FL_THIN_UP_BOX.