So you logged in to Facebook, saw a pop-up window, clicked on it and voila, your Facebook chat box has turned to a sidebar. Most Facebook users are not liking it. But you can get your old chat box back by simply following these two simple steps (only works for Mozilla):
1. Download this addons from https://addons.mozilla.org/en-US/firefox/addon/greasemonkey/
2. Install userscripts from http://userscripts.org/scripts/show/107159
Once installed, log out then log back in to your Facebook account. You can complete this in 3 minutes!