var ventanaPopup = null;
function showPopWin(url, title, width, height, returnFunc) {
    //if (window.showModalDialog) { // Si estamos en Internet Explorer
      //  var args = "dialogWidth:" + width + "px;dialogHeight:" + height + "px";
       // window.showModalDialog(url, "_blank", args);
    //} else { // Si estamos en cualquier otro navegador
	var myLeft = (screen.width-width)/2;
    var myTop = (screen.height-height)/2;
        var args = "width=" + width + ",height=" + height +",left="+myLeft+",top="+myTop;
        ventanaPopup = window.open(url, "_blank", args);
    //}
}