var addLoadEvent = function(func){
	var oldonload = window.onload;
	if (typeof window.onload != 'function'){
		window.onload = func;}
	else{
		window.onload = function(){
			oldonload();
			func();}}
}

var tableHover = function(){
	var trSet = document.getElementsByTagName("TR");
	for(var i = 0; i < trSet.length; i++){
		trSet[i].onmouseover = function(){
			this.oldClassName = this.className
			this.className = this.oldClassName + " over";}
		trSet[i].onmouseout = function(){
			this.className = this.oldClassName;}}
}

addLoadEvent(tableHover);