libdmx1 1:1.1.4-2 (amd64 binary) in ubuntu focal

 libdmx is an interface to the DMX extension for X, which allows a single
 server to be set up as a proxy spanning multiple servers -- not unlike
 Xinerama across discrete physical machines. It can be reconfigured
 on the fly to change the layout, and it is presented as a single logical
 display to clients.
 .
 libdmx allows clients to configure the layout of DMX servers by adding
 and removing screens, input devices, et al.
 .
 More information about X.Org can be found at:
 <URL:https://www.X.org>
 .
 This module can be found at
 https://gitlab.freedesktop.org/xorg/lib/libdmx