Note: some of you may notice that a reboot entry is already defined in systemui.xml. However, it utilizes osso-powerup-shutdown and preforms a very brutal shutdown. Rebooting with sudo reboot will gently shutdown all software and sync your filesystems, which is safer. Let’s just say that there was probably a reason that the default entry was commented out.
Save the file, exit the editor and reboot your N900.
Enjoy your newly added Reboot button which will perform a safe reboot once pressed!