Listbox setSelected( ) depending of the value of the ListItem

<zscript>
   Person person = new Person("ERT-2009-0001", "Actif", "RST", 1, Calendar.getInstance()) ;   
   groups = new String[] {"ERT", "RST", "CCT", "testg"};
</zscript>
....
         <row>
            <label value="Group" /> 
            <hbox>            
               <listbox rows="1" mold="select" selectedItem="@{person.group}">
                  <listitem label="${each}" value="${each}" forEach="${groups}"

 
                  />               
               </listbox>
               <image src="img/QuestionmarkButton-16x16.png" tooltip="h_group" popup="h_group" style="cursor:help;"/>
               <label value="@{person.group}"/>               
            </hbox>
         </row>
...