New screen editor feature in System 59.

[Daniel L. Weinreb <dlw at MIT-AI>]

The screen editor in System 59 has a new command called "Create
(expand)".  It is like the "Create" command, except that instead of
asking you for the upper-left and lower-right corners for the new
window, it instead asks you for a single point, and creates a window
that fills up all the area around that single point.  It is just like
creating a tiny window at that point with "Create", and then using
"Expand Window" on it.  This command lets you say "...and now fill the
rest of this area with a Supdup window.".