Hiding text in a fred-window

[Josh Lubell <lubell@cs.UMD.EDU>]

I'm building a program editing environment in MCL 2.0 (alpha) where
the text the user types in is in :PLAIN style, and delimeters
corresponding to the language's BNF are displayed in :BOLD style.  I
want to give the user the ability to toggle back and forth between
displaying and hiding the delimiters.

Therefore, I need to be able to make a fred-window that can suppress
the displaying of any of its boldface text.  However, I cannot simply
delete any characters from the window's buffer-mark with :BOLD style,
since I need to be able to redisplay all text (bold and non-bold)
later on.

Any suggestions?  Please respond to me directly (lubell@cs.umd.edu),
and I will post a summary of the replies.

Josh