function cancel_bubble(evt) {
     evt = evt || window.event;
     evt.cancelBubble = true;
    }


    function show_hide(id) {
      var popup=document.getElementById(id);
      if(popup.style.display=='block') {popup.style.display='none'} else {popup.style.display='block'}
    }


    function _show_hide(id) {
      if((current_shown!="")&&(current_shown!=id)) if(document.getElementById(current_shown)) document.getElementById(current_shown).style.display="none";
      var popup=document.getElementById(id);
      if(popup.style.display=='block') {
       popup.style.display='none';
       current_shown="";
      }
      else {
       hide_popups();
       popup.style.display='block';
       current_shown=id;
      }
    }