fix for hiding/showing optgroups when optionlist is hidden
fix for hiding/showing optgroups when optionlist is hidden

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