function getElementsByClass(searchClass,node,tag) {
	var classElements = new Array();
	if ( node == null )
		node = document;
	if ( tag == null )
		tag = '*';
	var els = node.getElementsByTagName(tag);
	var elsLen = els.length;
	var pattern = new RegExp("(^|\\s)"+searchClass+"(\\s|$)");
	for (i = 0, j = 0; i < elsLen; i++) {
		if ( pattern.test(els[i].className) ) {
			classElements[j] = els[i];
			j++;
		}
	}
	return classElements;
}

//External
arr=getElementsByClass('external',document,'a');
for(x=0;x<arr.length;x++) {
	arr[x].onclick=function() {	
		window.open(this.href,'','');
		return false;
	}
	arr[x].onkeypress=arr[x].onclick;	
}
//Back
arr=getElementsByClass('back',document,'a');
for(x=0;x<arr.length;x++) {
	arr[x].onclick=function() {	
		history.back();
		return false;
	}
	arr[x].onkeypress=arr[x].onclick;	
}
//menuRoll
arr=getElementsByClass('menuRoll',document,'a');
var imagenDefault='';
for(x=0;x<arr.length;x++) {
	arr[x].onmouseover=function() {	
		imagen=this.previousSibling;
		imagen.src=imagen.src.replace('blank','seccion_rollover');
	}
	arr[x].onmouseout=function() {	
		imagen=this.previousSibling;
		imagen.src=imagen.src.replace('seccion_rollover','blank');
	}
}