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From: siegel@booga.Eng.Sun.COM (Josh Siegel)
Newsgroups: comp.windows.news
Subject: Re: Hunh? (locked send contexts)
Message-ID: <139221@sun.Eng.Sun.COM>
Date: 19 Jul 90 21:23:53 GMT
References: <9007161732.AA01251@> <1990Jul19.153846.1586@canon.co.uk>
Sender: news@sun.Eng.Sun.COM
Organization: Sun Microsystems, Mt. View, Ca.
Lines: 57

In article <1990Jul19.153846.1586@canon.co.uk> laukee@canon.co.uk (David Lau-Kee) writes:
>bice@hbo.UUCP (Brent A. Bice) writes:
>
>...
>>entry I want to have a function that will spawn a completely independent
>>window.  When the main window gets Zap'd, it should go away, but not kill
>>the window/s that it spawned.  I have a piece of code that does this, but
>>the main window won't die until all of the other window/s that it spawned
>>also are zapped.   Howcomeforwhy?   Am I missin' somethin' here?

Below is the code:
    /MainDict /ThisIsIt def
    
    % Make a window with a new processgroup and a clean environment.
    /makewin {
             {
                % Clean up dictionary stack
                {
                   currentdict /MainDict known { exit } if
                   end
                } loop
                clear   % clean up regular stack
                newprocessgroup
                framebuffer /new LiteWindow send dup
                /reshapefromuser exch send   /map exch send
             } fork pop
    } def
    
    
    % Here's the main window.  It has a menu entry that merely calls makewin.
    framebuffer /new LiteWindow send
    dup {
       /ClientMenu [
          (MAKEWIN)    { makewin }
       ] /new DefaultMenu send def
    } exch send
    dup /reshapefromuser exch send
    /map exch send

Problems,
  A send command locks the DictStack so that you cannot "end" your
way into a class dictionary.  Under NeWS 2.0, this generates
a dict_underflow error.  Under some other versions of NeWS, I think
this fails silently (I don't remember which ones).  The proper 
solution is to replace:

                {
                   currentdict /MainDict known { exit } if
                   end
                } loop

 with
                clearsendcontexts

and get rid of the /MainDict noise.

    --josh