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

String.prototype.trim = function() {
	return this.replace( /^\s+|\s+$/, "" );
}

function addClassName (elem, className) {
	removeClassName (elem, className);
	elem.className = (elem.className + " " + className).trim();
}

function removeClassName (elem, className) {
	elem.className = elem.className.replace(className, "").trim();
}

function getElementsByClassName(classname,tag) {
	if(!tag) tag = "*";
	var anchs =  document.getElementsByTagName(tag);
	var total_anchs = anchs.length;
	var regexp = new RegExp('\\b' + classname + '\\b');
	var class_items = new Array()

	for(var i=0;i<total_anchs;i++) 
	{ 
		var this_item = anchs[i];
		if(regexp.test(this_item.className)) {
			class_items.push(this_item);
		}
	}
	return class_items;
}