How do I get the current url inside a firebug extension?

How do I get the current url inside a firebug 开发者_运维问答extension when for example pressing a button?

Does that mean you create an extension for Firebug? I am not sure about that, but in extensions for Firefox you can get it with

window.content.document.location

Sorry if I misunderstood the question, it is not totally clear to me.

Just hover the element and right click to select "Inspect Element" to view details.