function openWindow(parametros, ancho, alto) {
		derecha=(screen.width-ancho)/2;
		arriba=(screen.height-alto)/2;
		string="toolbar=0,scrollbars=0,location=0,statusbar=0,menubar=0,resizable=1,width="+ancho+",height="+alto+",left="+derecha+",top="+arriba+"";
			
		fin=window.open('popup.php?'+parametros,"ventana", string);
	}

function dimensionar(ancho, alto, centro) {
	if(centro==true) {
		derecha=(screen.width-ancho)/2;
		arriba=(screen.height-alto)/2;
		window.moveTo(derecha,arriba);
	}
	
	window.resizeTo(ancho,alto);
}

function darFoco(id) {
	id = document.getElementById(id);
	if(id)  {
		id.focus();
	} else {
		self.focus();
	}
}

function doPost(frm, params) {
	var frm = document.getElementById(frm);
	if(frm) {
		frm.action = params;
		frm.submit();
	}
}

function getCookieVal (offset) {
 var endstr = document.cookie.indexOf (";", offset);
 
 if (endstr == -1)
  endstr = document.cookie.length;
  
 return unescape(document.cookie.substring(offset, endstr));
}

function getCookie (name) {
 
 
 var arg = name + "=";
 var alen = arg.length;
 var clen = document.cookie.length;
 var i = 0;
 
 while (i < clen) {
  var j = i + alen;
  
  if (document.cookie.substring(i, j) == arg)
   return getCookieVal (j);
   
  i = document.cookie.indexOf(" ", i) + 1;
  
  if (i == 0) 
   break; 
 }

 return null;
}

function setCookie (name, value) {
 var argv = setCookie.arguments;
 var argc = setCookie.arguments.length;
 var expires = (2 < argc) ? argv[2] : null;
 var path = (3 < argc) ? argv[3] : null;
 var domain = (4 < argc) ? argv[4] : null;
 var secure = (5 < argc) ? argv[5] : false;
 
 path="/";
 
 document.cookie = name + "=" + escape (value) +
 ((expires == null) ? "" : ("; expires=" + expires.toGMTString())) +
 ((path == null) ? "" : ("; path=" + path)) +
 ((domain == null) ? "" : ("; domain=" + domain)) +
 ((secure == true) ? "; secure" : "");
}
function enviar()
 {
 var valor = document.form2.marcas.options[document.form2.marcas.selectedIndex].value; 
 //alert (valor);
 window.location = 'categorias.php?idcat='+valor;
 
 
 }