var image_over;
var image_out;

function changeImage(id)
{  
	if(document.getElementById)
	{
	  var element, style;

	  if ((element = document.getElementById(id))) {
        if ((style = element.style)) {
          style.backgroundImage = 'url("'+image_over+'")';
        }
      }
	}
}

function restoreImage(id)
{  
	if(document.getElementById)
	{
	  var element, style;

	  if ((element = document.getElementById(id))) {
        if ((style = element.style)) {
          style.backgroundImage = 'url("'+image_out+'")';
        }
      }
	}
}

function init()
{
	image_1 = new Image();
	image_2 = new Image();
	image_1.src = "fileadmin/template/images/sidenavi_over.gif";
	image_2.src = "fileadmin/template/images/sidenavi_out.gif";
	image_over = image_1.src;
	image_out = image_2.src;
}