Mouse handler table inconsistency.

[barmar@Think.COM]

   Date: Thu, 5 Apr 90 14:01 PDT
   From: Spock@SAMSON.cadr.dialnet.symbolics.com (Mr. Spock)

   I bet there is a problem with the table.  I have a similar type of
   lossage happening in the character-style mapping table.  I have an
   initialization that causes the file-server>init.lisp file to be read at
   boot time.  This file has sys:enable-services in it.  Every once in a
   while when booting the machine it will go into the debugger before
   getting to the initial lisp-listener.  The error is something like "No
   mapping for swiss.roman.normal ...".  The name of the style sometimes
   differs but it's always a style that *should* be defined.  It usually
   happens when trying to set up the domain-name server log.  It was hard
   to trace but as far as I could tell the table that is used for mapping
   character-styles to fonts was mutating and didn't get locked correctly
   so I wouldn't be surprised if there's a subtle bug in the mutating code.
   We all know how hard it is to mutate.  (I fixed this by forcing the
   lookup to be repeated if it returns NIL the first time.  And, yes I
   reported this.)  I've seen this in 7.2 and 7.2.2 and I think 7.1.

I've also seen this on random occasions.  And it isn't fixed in 8.0, as I
saw it a couple of days ago.  I c-m-R'ed the frame and it worked.