XUL and JavaScript question

Whoops! Solved...

content.document.location

Sorry...

Ok, here is the solution, just using the content.document.location

URLActual = content.document.location; // Global variable

//This function is executed when another toolbar button is pressed

function Activar()
{
var boton2 = null; // Old and rusty programmer habit

var boton2 = document.getElementById("myextension-button2");
// That's the button in firefox's toolbar, where I want to show the current URL

URLActual = content.document.location;

if (boton2.disabled==false)
boton2.disabled = true; //I enable the button if disabled
else
boton2.disabled = false;
boton2.label = URLActual; // And I change the label

}

Now, what I would like to do is to refresh the global variable "URLActual" every time the url changes, I'm fighting with that right now...