tvtwm is an X window manager derived from twm to which it adds the virtual desktop feature from swm. All of these window managers were originally written by Tom LaStrange. The current maintainer of tvtwm is Chris Ross.
Unlike most more recent virtual window managers, tvtwm models the root window as a single large space, with the physical desktop being a viewport onto that virtual root window. The user can scroll the viewport around the virtual desktop either by pressing certain keys or by clicking into a scaled down representation of the virtual desktop, the so-called panner.