GNOME-classic

Starting from GNOME 3.20, it's necessary to specify the GNOME_SHELL_SESSION_MODE=classic parameter to run a GNOME-classic session. This change has been introduced to solve: https://bugzilla.gnome.org/show_bug.cgi?id=720894

In order to run GNOME-classic virtual desktops with NoMachine on Linux distributions such as RHEL 7 or Fedora 22 and CentOS 7, edit the /usr/NX/etc/node.cfg file and set the DefaultDesktopCommand key as it follows:

DefaultDesktopCommand "env GNOME_SHELL_SESSION_MODE=classic gnome-session --session gnome-classic"

or to use dbus-launch:

DefaultDesktopCommand "env GNOME_SHELL_SESSION_MODE=classic /bin/dbus-run-session gnome-session"

GNOME-flashback

"GNOME Flashback is a session for GNOME 3 which was initially called "GNOME Fallback", and shipped as a stand-alone session in Debian and Ubuntu. It provides a similar user experience to the GNOME 2.x series sessions." (https://wiki.gnome.org/Projects/GnomeFlashback)
 

GNOME Flashback should run faster when Metacity compositing is disabled.

GNOME themes uses the drop shadow of the compositor as a hot-spot for resizing windows. So, when the compositor is disabled, the resize area is only 1 pixel wide. A possible solution to facilitate users to grab corners for resizing windows is to modify the GNOME theme to have for example a 5 pixel border.

To run GNOME flashback virtual desktops with NoMachine on Ubuntu 18.04 (Bionic Beaver)

1) Create a file named 98gnome-flashback-wants into the /etc/X11/Xsession.d/ directory, with this content:

if [ "$XDG_CURRENT_DESKTOP" = "GNOME-Flashback:GNOME" ] ; then
    WANTS=`sed -n -e 's/Wants=\(.*\)/\1/p' /usr/lib/systemd/user/gnome-session-flashback.target`
    for I in $WANTS ; do
            systemctl --user start $I
    done
fi

2) Ensure that the 98gnome-flashback-wants file has the same ownership and permissions of the other files in the
/etc/X11/Xsession.d/ directory.

3) Edit the /usr/NX/etc/node.cfg file and set:

DefaultDesktopCommand "env XDG_CURRENT_DESKTOP=GNOME-Flashback:GNOME /etc/X11/Xsession 'gnome-session --session=gnome-flashback-metacity'"

To run GNOME flashback virtual desktops with NoMachine on Ubuntu 16.04, edit the /usr/NX/etc/node.cfg file and set any of the following:

a) to use Metacity window manager

DefaultDesktopCommand "env XDG_CURRENT_DESKTOP=GNOME-Flashback:Unity /etc/X11/Xsession 'gnome-session --session=gnome-flashback-metacity'"

b) to use Compiz window manager

DefaultDesktopCommand "env XDG_CURRENT_DESKTOP=GNOME-Flashback:Unity /etc/X11/Xsession 'gnome-session --session=gnome-flashback-compiz'"