ManaGeR or MGR is an early windowing system originally designed and developed for Sun 2/120 workstations in 1984 by Stephen A. Uhler, then at Bellcore.
MGR features overlapped, asynchronous windows and an applications interface that was both machine and network independent.
It is controlled by mousing pop-up menus, by keyboard interaction, and by escape sequences written on pseudo-terminals by client software.
[1] The entire MGR source code was posted to the comp.sources.unix Usenet newsgroup, Volume 17, Issue 1, in January 1989.
MGR ran on at least these systems: SunOS on Sun workstations (the original development platform),[5] Apple Macintosh, Unix System V on the AT&T UNIX PC, Ultrix on the DECstation 3100, MiNT on the Atari ST, OS-9, Coherent, Linux, FreeBSD and VSTa.