Add the X-GNOME-Settings-Panel category. You need a control-center
panel to add this to your desktop file. Desktop entries with this
category but that aren't actually panels will be ignored (no cheating).
If the desktop file for your settings isn't a panel, it will show in the
"Other" section of the control-center shell
https://bugzilla.gnome.org/show_bug.cgi?id=630998
This involves storing the default window title and icon name and resetting
the title and icon name when an embedded settings panel is closed.
The icon name and title for each panel is retrieved from the desktop file
information and stored in the CcShellModel.
