/**
 * @author extjs
 */
function   removeStyleSheet(id){
	var existing = document.getElementById(id);
	if(existing){
	   existing.parentNode.removeChild(existing);
	}
}
function swapStyleSheet(id, url){
	removeStyleSheet(id);
	var ss = document.createElement("link");
	ss.setAttribute("rel", "stylesheet");
	ss.setAttribute("type", "text/css");
	ss.setAttribute("id", id);
	ss.setAttribute("href", url);
	document.getElementsByTagName("head")[0].appendChild(ss);
}