(Build 2001021020) It happens to me very often, that the status line already says "There are no new messages on the server.". In this case, When I click 'Get Msg' and there are no new messages, I get no visual information that mozilla has reacted to my request (by contacting the server), because the status line does not change. I expect seeing something like "contacting server for new messages ..." for a short time, to know that I haven't missed the button :)
I'm sorry that mailnews is so blazingly fast. Seriously though, you'll just have to trust the status bar; if it says "No new messages on the server." then it means that. I think this bug is invalid.
Hwaara, no this is not invalid. See my comments in bug 68727 for why it's not. *** This bug has been marked as a duplicate of 68727 ***