One thing that always annoys me about Facebook is the quick-reply functionality in Facebook Messages. When the ↵-checkbox is checked or unchecked (I don’t know which state it is) hitting the enter key submits the message, instead of starting a new line.
They are using the correct character, that’s not the problem. The problem is that it’s not clear what it means if the checkbox is checked or unchecked. The tooltip (“Quick reply mode: press Enter to send”) is not helpful either, because it’s the same for both the checked and unchecked state!
I’ve had my messages cut short and sent more than once (and of course I didn’t note down what the checkbox state was at the time). So now I work around the problem by hitting shift+enter when I want to start a new line. That always works as I expect.
How Facebook could easily fix this
Facebook could simply show a different tooltip dependent on the checkbox state and make it clear whether quick reply mode is on or off.
Or they could hide the Reply-button when quick reply mode is on. It takes more balls to do that, but they’ve done that for wall comments as well so people using Facebook are quite used to it.
Update: cool, Facebook is now actually hiding the Reply-button to make the checkbox state clear.