Re: What does this mean?
When you get done typing your message or post or whatever it may be, but before you send it, right-click on your message, hit Select All, right-click on it again and hit Copy.
Then when you go to send your message if it doesn't go and you lose it, at least you'll still have it "in the mouse" (in the Clipboard) so you can simply paste it if you need to try to send again.