Multiple virtual desktops are supported. A virtual desktop may be bigger than the physical screen, in which case the current viewport on the desktop may be moved around, as described in the Viewports entry. Desks are identified by integers. There is currently an arbitrary limit on the number of desks, but it should be much higher than anyone will ever need. You can change the current desk with set-current-desk!; find out what the current desk is with current-desk; and set the desk a window is on with set-window-desk!.