Well, there was a lot of protest came from die hard Facebook people when they found the facebook chat feature changed without any notification or reverting options. But thanks(?) to the facebook developer team that they dint change or disable their old popout chat link yet. You might have noticed these chats in old browser versions. It was not as good as the previous ones, but still, its much better than the current chat feature. You can access your groups and the most important thing i.e. SCROLL-BARS!! It may look little odd as it opens in a new tab but still its very handy to use. Follow the steps given below.
1st way to get your old Facebook chat box
1. Log in to your Facebook account.
2. Click on the link given below. ( You might need to open link in a new tab)
3. You may bookmark this link and manage it from the toolbar.
2nd way to get old Facebook chat console using browser add-on/script
If u really want to get the something like replica of old Facebook chat, I suggest you to use this add-on/script for your browser.
1. For GOOGLE CHROME browser install Facebook-Chat-enhancer script.
2.For Firefox user grab Facebook-chat-enhancer script from here, but note that you must install Grease monkey ADD-ON, before using this script.
if you face any difficulties kindly put your comment below,we will try to solve your queries.
[note]There are many add-ons/extensions/Grease-monkey scripts released from few developers but they are having few integrity problems and might not work very well. [/note]