libdmx-dev binary package in Ubuntu Trusty amd64

 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.
 .
 This package contains the development headers for the library found in
 libdmx1. Non-developers likely have little use for this package.
 .
 More information about X.Org can be found at:
 <URL:http://www.X.org>
 .
 This module can be found at
 git://anongit.freedesktop.org/git/xorg/lib/libdmx

Source package