Wikipedia
X.desktop
X.desktop was an early desktop environment graphical user interface built on the X Window System. It was developed and sold during the late 1980s and early 1990s by IXI Limited, a British software house based in Cambridge. Versions of X.desktop were available for over 30 different UNIX operating system platforms and it was licensed to various vendors, including Compaq, Locus Computing Corporation, BiiN and Acorn Computers. Early version of X.desktop used Xlib and the Athena widgets; from version 2.0 onwards it was based on the Motif toolkit.