function showXULPage(ele){
	//var url = escape( 'http://developer.mozilla.org/en/docs/XUL:' +  ele);
	var url = ( 'http://developer.mozilla.org/en/docs/XUL:' +  ele);
	var fra = document.getElementById('main-manual-frame');
	//alert(fra);
	fra.setAttribute('src',url )
}

<iframe src="about:blank"  id="main-manual-frame"  flex="1"/>