function switchlang()
{
	var loctop  = parent.topfr.location.href;
	var locmain = parent.main.location.href;
	
	/* etwaige bestehende Parameter entfernen */
	if(loctop.match(/\?.*$/))
	{
		var loctop  = loctop.replace(/\?.*$/,"");
	}
	if(locmain.match(/\?.*$/))
	{
		var locmain = locmain.replace(/\?.*$/,"");
	}
	
	/* neue Parameter anhängen */
	var newtop  = loctop+'?lang=en';
	var newmain = locmain+'?lang=en';
	
	/*alert(loctop+"\n"+newtop+"\n\n"+locmain+"\n"+newmain);*/
	
	parent.topfr.location.href  = newtop;
	parent.main.location.href = newmain;
}