function toggleVisibility(el)
{
 if (el.style.display == 'none') {
  el.style.display = 'block'; 
 } else {
  el.style.display = 'none';
 }
}

function switchVisibility(show_id,hide_id)
{
	show_el = document.getElementById(show_id);
	show_el.style.display = 'block';
	hide_el = document.getElementById(hide_id);
	hide_el.style.display = 'none';
}