Fix IE JS Error if first item is disabled
Fix IE JS Error if first item is disabled

If the first item is disabled, it cannot be focused. This raises a
JS error in IE8 (and probably other versions).

Make sure we find the first item that is not disabled and focus this.

SomethingSexy/jquery-ui-multiselect-widget,r4j4h/jquery-ui-multiselect-widget,GerHobbelt/jquery-multiselect,SomethingSexy/jquery-ui-multiselect-widget,mcl-de/jquery-ui-multiselect-widget,PANmedia/ui-multiselect-dropdown,r4j4h/jquery-ui-multiselect-widget,gs-akhan/jquery-ui-multiselect-widget,gs-akhan/jquery-ui-multiselect-widget,gs-akhan/jquery-ui-multiselect-widget,GerHobbelt/jquery-multiselect,mcl-de/jquery-ui-multiselect-widget,PANmedia/ui-multiselect-dropdown,GerHobbelt/jquery-multiselect,SomethingSexy/jquery-ui-multiselect-widget,mcl-de/jquery-ui-multiselect-widget