# "-anchor" specifies how the information in a widget (e.g. 
# text or a bitmap) is to be displayed in the widget. Must 
# be one of the values n, ne, e, se, s, sw, w, nw, or 
# center. For example, nw means display the information 
# such that its top-left corner is at the top-left corner 
# of the widget. 

$mlistbox->configure(-anchor => 'e'); # or 'center'