Binary package hint: metacity
All applications launched from gnome-panel launchers, menu, or alt-f2 share the same pgid. Gnome developers claim this is not typical behavior for the panel, so may be a result of an Ubuntu customization. The same applications launched from the terminal do NOT share PGID. This is a problem for several reasons (some highlighted in this forum thread: http://www.ubuntuforums.org/showthread.php?t=347023):
1. Pressing Ctrl+C in Matlab with shared PGID closes gnome-panel.
2. fbpanel cannot raise applications via the taskbar with the shared PGID (it can raise applications fine if they don't share PGID). The applications receive focus, but do not raise. This may also tie into metacity, as it may not be a problem with other window managers, but again I think it is Ubuntu-specific. Note that the windows properly receive focus, they just don't raise.
3. Python's IDLE environment fails to raise the shell window when that window receives focus (e.g., by pressing F5) after the initial opening. This is only true if running metacity, e.g., xfwm4 properly raises that window each time it receives focus.
I submit this as a single bug report, because it appears to be an issue in how the customized gnome build Ubuntu provides handles raising windows and sending focus when applications share a pgid (which is really a metacity problem, but it is compounded by the odd gnome-panel behavior). This is true at least in release 6.10.
Thank you for your bug. Where did GNOME developers claimed that? There is no Ubuntu specific patch likely to do that and they have different PID for other peope, you are the first to get that problem. Did you make some changes over a default installation that could lead to that problem?