I’d been searching for a fix for this bug in Xubuntu where the Network manager icon/applet (nm-applet) is missing in the System tray in Xubuntu 14.04. On trying to launch it manually, it runs, but icon is still missing. Apparently that’s because normal users are unable to launch nm-applet on Xubuntu 14.04 due to a bug, according to Paul Bauer, as described in his article here.
He also describes a solution which worked for me. This entails launching nm-applet with dbus-launch.
Edit the file as root:
gksu gedit /etc/xdg/autostart/nm-applet.desktop
And change the line:
On restarting the Network Manager applet is back.