var lastname='ident';
function toggle(name)
{
   var elt_a = document.getElementById('a_'+name);
   var elt = document.getElementById(name);

   var old_elt_a = document.getElementById('a_'+lastname);
   var old_elt = document.getElementById(lastname);

   try{
      old_elt.style.display='none';
   }catch (e) {}

   try{
      old_elt_a.className='a_normal';
   }catch (e) {}


   try{
      elt.style.display='block';
   }catch (e) {}

   try{
      elt_a.className='a_hover';
   }catch (e) {}

   lastname=name;

}