function lib_bwcheck()
{ //Browsercheck (needed)
	this.ver=navigator.appVersion.toLowerCase();	
	this.agent=navigator.userAgent.toLowerCase();	
	this.mac=this.agent.indexOf("mac")>-1;
	this.lnx=this.agent.indexOf("konqueror")>-1;
	this.win=this.agent.indexOf("windows")>-1;
	this.unx=this.agent.indexOf("x11")>-1;
	this.so=(this.mac || this.lnx || this.win || this.unx);	
	this.dom=document.getElementById?1:0;
	this.opera5=this.agent.indexOf("opera 5")>-1;
	this.ie6=(this.ver.indexOf("msie 6")>-1 && this.dom && !this.opera5)?1:0;
	this.ie5=(this.ver.indexOf("msie 5")>-1 && this.dom && !this.opera5)?1:0;	
	this.ie4=(document.all && !this.dom && !this.opera5)?1:0;
	this.ie=(this.ie4||this.ie5||this.ie6);		
	this.ns=this.agent.indexOf("netscape");		
	if (this.ns>-1){		
		this.ns7=(this.agent.substring(this.ns, this.agent.length).indexOf("7")>-1)?1:0;			
		this.ns6=(this.agent.substring(this.ns, this.agent.length).indexOf("6")>-1)?1:0;
	}
	this.ns4=(document.layers && !this.dom && this.agent.indexOf("netscape")>-1)?1:0;
	this.ns=(this.ns7||this.ns6||this.ns4);
	this.saf=this.agent.indexOf('safari')>-1;
	this.bw=(this.ie6 || this.ie5 || this.ie4 || this.ns4 || this.ns6 || this.ns7 || this.opera5 || this.saf);
	return this;
}

//cambia la clase de un objeto
function cambioClase(obj,clase)
{
 obj.className=clase
}