//元素名称：m_n; tab_m_n
//count:交换的个数
function showtab(m,n,count,a){
	for(var i=1;i<=count;i++){
		if (i==n){			
			getObject("td_"+a+"_"+i).className="libg"+a;
			getObject("tab_"+a+"_"+i).className="show";
			}
		else {
			getObject("td_"+a+"_"+i).className="libgs"+a;
			getObject("tab_"+a+"_"+i).className="hidden";
			}
	}
}
function getObject(objectId) {
    if(document.getElementById && document.getElementById(objectId)) {
	// W3C DOM
	return document.getElementById(objectId);
    } else if (document.all && document.all(objectId)) {
	// MSIE 4 DOM
	return document.all(objectId);
    } else if (document.layers && document.layers[objectId]) {
	// NN 4 DOM.. note: this won't find nested layers
	return document.layers[objectId];
    } else {
	return false;
    }	
}
<!--	
	function CheckLogin(){
	  var taget_obj = document.getElementById('_userlogin');
	  myajax = new DedeAjax(taget_obj,false,false,'','','');
	  myajax.SendGet2("http://www.pgpop.com/member/ajax_loginsta.php");
	  DedeXHTTP = null;
	}
-->