Fullscreen across all monitors doesn't work when no window manager is running

Resizing the NoMachine client  window across all monitors in a multiple monitor setup or configuring fullscreen across all monitors does not have the desired effect when no window manager is running.

This issue has been reported for Ubuntu 12.04 on server and client side, ATI's fglrx driver and two 1920x1200 displays.

The client either maximizes the session window on one screen, or, if explicit -geometry settings are set, make it appear for a while at the desired location and suddenly resizes itself so that the window is half-off the screen to the right.