With gmixer-1.3-6.fc12 and other packages current from rawhide, when I run gmixer from the command line, do what needs to be done, and then close the gmixer window, the gmixer process stays running and I have to kill it. It should exit, no?
*** Bug 520975 has been marked as a duplicate of this bug. ***
I think it doesn't quit on closing the window but continues to run in the system tray. Unfortunately the tray icon is broken, see bug 521915.