function expand(element)
{
  element.style.display='block';
  var id='b_' + element.id;
  var foto=document.getElementById(id);
  foto.src='/test/templates/default/gfx/b_minus.gif';
}

function collapse(element)
{
  element.style.display='none';
  var foto=document.getElementById('b_' + element.id);
  foto.src='/test/templates/default/gfx/b_plus.gif';
}

function tree(id)
{
  element=document.getElementById(id);
  if(element.style.display=='none'  || element.style.display=='')
    expand(element);
  else
    collapse(element);
}