The only file required in an MGR installation is the server itself. That would give you terminal emulator windows with shells running in them and cutting and pasting with the mouse, but no nice clocks, extra fonts, fancy graphics, etc. Depending on options, a monochrome server needs about 200K of RAM plus dynamic space for windows, bitmaps, etc.
If /usr/mgr/bin is in your PATH, then just type "mgr" to start up. After enjoying the animated startup screen, press any key. When the hatched background and mouse pointer appear, hold down the left mouse button, highlight the "new window" menu item, and release the button. Then drag the mouse from corner to corner where you want a window to appear. The window will have your default shell running in it. Hold down the left mouse button over an existing window to see another menu for doing things to that window. Left-clicking on an obscured window raises it to the top. The menu you saw that pops-up over the empty background includes the quit command. For people with a two button mouse: press both buttons together to emulate the missing middle button used by some clients.
The quit submenu includes the "really quit" option, a suspend option which should only be used if you run a job-control shell, and a screen saver and locker option, which waits for you to type your login password when you come back to your machine.
When trying to run MGR, if you get:
make sure you have a /dev entry for your display device, e.g. on a Sun /dev/bwtwo0. If not, as root cd to /dev, and type "MAKEDEV bwtwo0". Otherwise, you might need the -S/dev/bwtwo0 or (on Linux) the -S640x480 command line option when starting mgr. On Linux, you might also make sure that /usr/mgr/bin/mgr was installed setuid root.
make sure /dev/mouse exists, usually as a symbolic link to the real device name for your mouse. If you haven't permission to write in /dev, then something like a -m/dev/cua0 option can be given when starting mgr. Also, make sure you've supplied the right mouse protocol choice when you configured mgr. The mouse may speak Microsoft, even if that is not the brand name.
make sure all of /dev/[tp]ty[pq]? are owned by root, mode 666, and all programs referenced with the "shell" option in your .mgrc startup file (if any) exist and are executable.
make sure MGR is looking in the right place for its fonts. Check the Configfile in the source or see whether a -f/usr/mgr/font option to mgr fixes the problem.
login to your machine from another terminal (or rlogin) and kill the mgr process. A buckey-Q key can quit MGR if the keyboard still works.
Any tty-oriented application can be run in an MGR window without further ado. Screen-oriented applications using termcap or curses can get the correct number of lines and columns in the window by your using shape(1) to reshape the window or using set_termcap(1) to obtain the correct termcap entry.
converts some BDF fonts to MGR fonts
an icon browser
bury this window
vi menus from C compiler errors
digital display of time of day
analog display of time of day
close this window, iconify
set the foreground and background color for text in this window
read or write in the color lookup table
change appearance of the character cursor
cut text from this window into the cut buffer
display a sequence of icons
crude ditroff previewer
fade a home movie script from one scene to another
change to a new font in this window
a groff to PBM driver using Hershey fonts
hp 2621 terminal emulator
animate an icosahedron or other polyhedron
notification of mail arrival
message arrival notification
iconify and deiconify windows
load a font from the file system
a maze game
micky mouse clock
create or select a pop-up menu
bellcore window system server and window manager
boulder-dash game
watch mailbox for mail and notify
graph of system load average
lock the console
graphical login controller
magnify a part of the screen, optionally dump to file
notification of mail arrival
set or clear window modes
message arrival notification
Unix "plot" graphics filter
sandclock
browse through mgr fonts
a sketching/drawing program
view mgr bitmap images
start up less/more in separate window, menu added for less
startup up any program in a separate, independent window
display the current phase of the moon
start up vi in a separate window, with mouse pointing
(old) close a window
(old) notification of mail arrival
convert raw PBM/PGM/PPM image files to mgr bitmap format
split out a stream of bitmaps
printer output from PBM
ghostscript patch and front end, a PS viewer
a bitmap browser, or image viewer
cleanup window state after client crashes messily
rotate a bitmap 90 degrees.
write graphics screen dump to a bitmap file
redirect console messages to this window
output an appropriate TERM and TERMCAP setting
name a window, for messages and iconifying
reshape this window
square this window
compress mgr bitmap using run-length encoding
produce a skeleton startup file for current window layout
TeX dvi file previewer
convert between mgr font format and text dump
uncompress mgr bitmap using run length encoding
convert between mgr font format and VGA
print an image of a window
an icon editor
graphics demos
on-screen calculator
frontend to /usr/games/chess
editor with lisp/term/mgr.el mouse & menu support
universal scientific data plotting
font design and creation
folding editor
portable bitmap format conversions, manipulations
slick scientific data plotting
The Emacs support in misc/mgr.el and misc/mailcap includes very usable MIME support, via Rmail and metamail.
A general image viewer could be cobbled together from pilot and the netPBM filters, but I have not taken the time to do it.