Comment 7 for bug 11462

There was actually a reason that firefox's .desktop file doesn't enable startup
notification.

If you run "firefox" once, it starts the app and displays a window. If you run
"firefox" again, it communicates with the running app and asks it to open a new
window.

With startup notification enabled as it is now, you get a busy cursor for the
first launch and everything works fine. For the second launch though, the
startup notification completion message is never broadcast, so you get a stuck
busy cursor (until it times out).

For Firefox to work correctly with StartupNotify=true, this problem would need
to be fixed.