title: Silently change url to previous using Backbone.js
body: <p>Using Backbone.js, is it possible to make the router navigate to the page where it came from? I'd like to use that for the case where I change my URL when a popup appears, and I want go change it back, when I hide the popup. I don't want to simply go back, because I want to keep the background page in precisely the same position as I left it before I showed the popup</p>