I had a small text file (about 30kB) opened and wanted to close it, clicked on the "cross", but nothing happened. I did this few times but without any success. Still it was possible to move the window, but wasn't possible to close it. I decided to kill it, but before I succeeded it had already closed on its own. I've been using mousepad for about 2 months and this has happened to me about 3-4 times. It hasn't happened with any other application I use, so I think it's problem just of the mousepad. Unfortunately I'm not able to reproduce it, it just VERY rarely happens. The time for what the application couldn't be closed was about 10 seconds. It's a lot of time, because the system reacts really fast, without any noticeable delay. The system - xubuntu 9.04, x86_64, quad core, 8GB memory
I have a similar problem. It's completely random here too, including the time it takes for Mousepad to shutdown. And it even happens when I just open it, type a few words and try to close it without saving.
I have been having similar trouble, consistently and reproducably. I suspect that this bug is the same as #5566 and 4917. If you are REAL patient, and wait up to 10 seconds (it seems like a lifetime, I know), Mousepad WILL eventually close. That doesn't make it any less of a bug . . .
*** This bug has been marked as a duplicate of bug 6228 ***