function popup(id, popupId)
{
  var obj = document.getElementById( id );
  var popup = document.getElementById( popupId );

  var frameWidth = 0;
  var frameHeight = 0;

  if ( popup.style.visibility == 'visible' )
  {
    popup.style.visibility = 'hidden';
  }
  else
  {
    if (self.innerWidth)
    {
	frameWidth = self.innerWidth+window.pageXOffset;
	frameHeight = self.innerHeight+window.pageYOffset;
    }
    else if (document.documentElement && document.documentElement.clientWidth)
    {
	frameWidth = document.documentElement.clientWidth+window.pageXOffset;
	frameHeight = document.documentElement.clientHeight+window.pageYOffset;
    }
    else if (document.body)
    {
	// IE
	frameWidth = document.body.clientWidth+document.body.scrollLeft;
	frameHeight = document.body.clientHeight+document.body.scrollTop;
    }

    popup.style.left =  (frameWidth/2)-(popup.clientWidth/2) + "px";
    popup.style.top =  frameHeight-popup.clientHeight-10 + "px";

    popup.style.visibility = 'visible';
    if (popup)
    {
      popup.onmouseover=function(){this.style.visibility='visible';}
    }
  }
}

function hide_popup(id, popupId)
{
  var obj = document.getElementById( id );
  var popup = document.getElementById( popupId );
  if ( popup.style.visibility == 'visible' )
  {
    popup.style.visibility = 'hidden';
  }  
}