var divCollection = document.getElementsByTagName("div");
	    
function SetZIndex(clickedDiv)
{
	for (var i=0; i<divCollection.length; i++) 
	{
		divCollection[i].style.zIndex = 0;
	}
	
	clickedDiv.style.zIndex = 2;
	var parentDiv = clickedDiv.parentNode;
	
	//check that the node is a tag, not text (type=3)
	if ((String(parentDiv.nodeName) == "DIV") && (parentDiv.nodeType == 1))
	{
		parentDiv.style.zIndex = 1;			
	}
}