function addRolloverEvents(obj,id,imageprefix,extension) {
	try {		
		obj.onmouseover = function(event){document.getElementById(id).src = imageprefix + '_over.' + extension;};
		obj.onmouseout = function(event){document.getElementById(id).src = imageprefix + '_up.' + extension;};
		obj.onfocus = function(event){document.getElementById(id).src = imageprefix + '_over.' + extension;};	
		obj.onblur = function(event){document.getElementById(id).src = imageprefix + '_up.' + extension;};
		obj.onmousedown = function(event){document.getElementById(id).src = imageprefix + '_down.' + extension;};
		obj.onmouseup = function(event){document.getElementById(id).src = imageprefix + '_over.' + extension;};
		obj.onkeydown = function(event){document.getElementById(id).src = imageprefix + '_down.' + extension;};
		obj.onkeyup = function(event){document.getElementById(id).src = imageprefix + '_over.' + extension;};
		var cache1 = new Image(); cache1.src = imageprefix + '_over.' + extension;
		var cache2 = new Image(); cache2.src = imageprefix + '_down.' + extension;
	}		
	catch(e){};
}