document.getElementsByClassName = function(cl, sTagName) {
	var retnode = [];  
	var myclass = new RegExp('\\b'+cl+'\\b');  
	var elem = this.getElementsByTagName((sTagName===""||sTagName===null)?"*":sTagName);  
	for (var i = 0; i < elem.length; i++) {  
		var classes = elem[i].className;  
		if (myclass.test(classes)) retnode.push(elem[i]);  
	}
	return retnode;  
}

window.onload = function(){
	/* Pop-ups */
	pops = document.getElementsByClassName("popup","a");
	pops_items = pops.length;
	ancho = 800;
	alto = 600;
	posx = (screen.width-ancho)/2;
	posy = (screen.height-alto)/2;
	for(i=0;i< pops_items;i++){

		pops[i].onclick = function(){
			ventana = window.open(this.href, "ventana", "width=" + ancho + ",height=" + alto + ",top=" + posy + ",left=" + posx + ",scrollbars=yes,statusbar=no,menubar=no");
			return false;
		}
	}
	

	/* Menu */
	menu = document.getElementById("cabecera").getElementsByTagName("div")[0].getElementsByTagName("ul")[0].getElementsByTagName("li");
	menu_items = menu.length;

	for(i=0;i<menu_items;i++){
		img_actual = menu[i].getElementsByTagName("a")[0].getElementsByTagName("img")[0];
		img_actual.onmouseover = function(){
			ruta = this.src;
			ruta_nueva = this.src.substring(0,this.src.length-4);
			ruta_nueva += "_on.gif"

			esta_on = this.src.indexOf("_on");
			if(esta_on == -1) this.src = ruta_nueva;
		}
		img_actual.onmouseout = function(){
			this.src = ruta;
		}
	}
}