Issue GC-MESSAGES (Version 1)

[David A. Moon <Moon@STONY-BROOK.SCRC.Symbolics.COM>]

This seems a little short-sighted.  GC messages aren't necessarily the
only unsolicited messages.  In the example application you gave, there
is no reason to treat GC messages differently from other messages.

Also, a simple on/off switch may be a bit too simple.  Not all systems
have windows, but for the ones that do a three-state switch could be
defined in an implementation-independent way: (1) turn the messages off,
(2) put them in the typescript, (3) make them visible to the user in a
way that doesn't interfere with the typescript.  Even some
teletype-oriented systems are able to implement option 3.

In some systems it may not be possible to implement this with a variable,
since changing the state of the switch may have to communicate with an
operating system written in some horrible language.  The safest thing would
be a macro, whose expansion is system-dependent, and within the dynamic
extent of the macro's body unsolicited messages are controlled.

I'm not very optimistic about the possibility of standardizing on this kind
of environmental issue, but perhaps some very simple facility to prevent
messing up of the screen can be agreed on.