I wondered if the list is based on a social relevancy algorithm and shows those friends whose content I like or comment upon most often. From Facebook’s chat help: Which friends appear in the sidebar? The list of friends in your sidebar is based on who you’ve interacted with most frequently or recently on Facebook.
To “go offline” (not available to chat to anyone): To go back online at any time and show your friends your available to chat, click the “Chat (Offline)” bar in the lower right:…then click the hyperlinked “available:”You can easily display the fact you’re online and available to chat with only certain friends. First, you’ll need to have Friend Lists set up (see #4 below). Or, try the nifty Circle Hack app, created toemulate the Google+ circles! Circle Hack is a really easy way to segment your Facebook friends – you don’t have to put everyone in a list, maybe just specific friends then leave others as they are.
(The Circle Hack app is not affiliated with Facebook.) click “Hide Sidebar.”At some point in the past few months, since Facebook has been rolling out the new Messages (email) product, you may have been taken aback to find a conversation history from a long time ago suddenly show up when emailing a friend.
The new Messages product is fully integrated with your email, chat and texting (if you use it).
If you don’t see the sidebar, just click Chat in the bottom right corner of your screen, which shows the same list of friends you’ll find in your sidebar.”To chat with any friend in the new sidebar, click on their name and the chat window opens up.
You’ll know when a friend is available to chat depending on the icon next to their name: Even if friends aren’t available to chat, you can still send them a message and they can read it later.
Chat messages are also viewable via the Messages (email) box.To chat with a friend not listed in the new sidebar, start typing their name in the search box at the bottom of the list. There are many ways to get back to your list of Friend Lists; one of the easiest ways is to remember the URL is simply facebook.com/friends.You may have noticed the new Facebook Chat Sidebar when you logged in to Facebook recently.The list of friends displayed in this sidebar is supposed to be the friends you interact with most.(A few friends and I are finding that the relevancy of the friends in this display is not that accurate!)I rarely use the Facebook chat feature, so I thought perhaps the select list of friends was ones I email most often, but it’s not.