HTML_QuickForm_advmultiselect (qfams) is designed as custom QuickForm element to emulates via two select boxes a select box that allows selecting of multiple options.
ability to double click on either select box to move elements from one side to the other
added headers to the select boxes
ability to change layout easily, using CSS classes and a mini template
allows to change item size shown of each multiple select box
ability to sort lists (by programming, or user-end handling)
display live counter (selected/unselected items count) Available since version 1.3.0