/usr/share/xsessions/kde-3.5.desktop
[Desktop Entry]
Encoding=UTF-8
Type=XSession
Exec=/usr/kde/3.5/bin/startkde TryExec=/usr/kde/3.5/bin/startkde
Name=KDE 3.5

/usr/share/xsessions/gnome.desktop
[Desktop Entry]
Encoding=UTF-8
Name=GNOME
Exec=gnome-session
TryExec=gnome-session
# no icon yet, only the top three are currently used
Icon=
Type=Application