As a fervent multi-monitor user, I ran into issues with the latest Ubuntu (9.04) in combination with Gnome and Eclipse. When I switched to another application which was (partially) overlapping Eclipse, I could not switch back to Eclipse by clicking the item in the taskbar. Nothing would happen, and if I clicked multiple times, the application would actually get hidden.
It happens to me on a quite frequent basis. I work in a Windows based editor for some time, and press ctrl+s every now and then to save my changes to disk. It turned kinda into a habbit. No big deal, unless… you start working in VI. Everytime, well, until now, when you press ctrl+s, it would hang up your session. Nothing you could do about it. It’s the most frustrating thing ever!