/*
function getElementsByClass(searchClass,tag) 
{
   var classElements = new Array();

   if ( tag == null )
      tag = '*';
   
   var els = document.getElementsByTagName(tag);
   var elsLen = els.length;
   var pattern = new RegExp("(^|\\s)"+searchClass+"(\\s|$)");

   for (i = 0, j = 0; i < elsLen; i++) 
   {
      if ( pattern.test(els[i].className) ) 
      {
         classElements[j] = els[i];
         j++;

      }
   }
   return classElements;
}
*/
function randomBgImage()
{
   var ns = (document.all)?false:true;
   var elID = 'mGabbia';
   
   images = new Array(4);
   images[0] = 'url(http://www.ospedaleniguarda.it/images/bg_body_1.jpg)';
   images[1] = 'url(http://www.ospedaleniguarda.it/images/bg_body_2.jpg)';
   images[2] = 'url(http://www.ospedaleniguarda.it/images/bg_body_3.jpg)';
      images[3] = 'url(http://www.ospedaleniguarda.it/images/bg_body_4.jpg)';
  
   index = Math.floor(Math.random() * images.length);

   if (ns)
   {
      elBg = document.getElementById(elID).style;
   } 
   else 
   {
      elBg = eval(elID + ".style");
   }

   elBg.backgroundImage = images[index];

}