When I start an external process (e.g. "evince Documents/fremd/emacs.pdf &") and then stop the terminal with Alt-F4, File.CloseWindow or the window close button the external process is killed also. Only if I use "exit" on the command line the external process continues. Seen under openSUSE 11.4. There is a maybe a similar bug: 8552
There is disown for that.