Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!cornell!rochester!rutgers!njin!princeton!phoenix!mbkennel
From: mbkennel@phoenix.Princeton.EDU (Matthew B. Kennel)
Newsgroups: comp.sys.next
Subject: Re: NextStep and NeWS...
Keywords: NextStep,NeWS,Postscript
Message-ID: <7898@phoenix.Princeton.EDU>
Date: 22 Apr 89 00:33:43 GMT
References: <1041@nixctc.DE> <8530@polya.Stanford.EDU> <3901@ficc.uu.net> <4779@pt.cs.cmu.edu> <3931@ficc.uu.net> <4792@pt.cs.cmu.edu>
Reply-To: mbkennel@phoenix.Princeton.EDU (Matthew B. Kennel)
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Organization: Princeton University, NJ
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In article <4792@pt.cs.cmu.edu> avie@wb1.cs.cmu.edu (Avadis Tevanian) writes:
>
>Yes, and we agree, we have a layer of NextStep known as the "packages" which
>is that part of NextStep that runs entirely in the window server.  It does
>things like window movement, activation, ...  And as it turns out, you
>as a user can load your own packages.  It doesn't allow to reimplement
>the entire UI, but then again, if you do that, you don't have NextStep
>anymore.  Remember, it makes little sense to reimplement window/menus/...
>at the NextStep layer, because you no longer have NextStep.  If you want
>to implement a different UI and allow for everything to be rewritten you
>can certainly do that in DPS.
>
>
>So, can we lay this to rest by saying that NextStep is a specific UI for
>which it make no significant sense to reimplement features and that if
>you want to have a UI in which any feature was user-implementable you
>could write it in DPS?

Ok, here's the big question.  Is the _user interface as seen by the
user_ separate from the window system?  Is the "toolkit interface" seen by the
programmer separate from the window system?  

Here's what I mean:  I can see that if somebody wanted to do a totally 
different kind of user interface, this programmer would have to create all
the structures &c and write the appropriate code to display them.  That's fine,
you can't expect the given system to be omniscient enough to do everything
for you.

But here's the other question: can you replace the code & 
appearance/superficial features of the user interface, but maintain the
same programmer interface so that existing programs will work in this
new way without change?  For example, taking a Mac analogy, I might want to
make some window type with a "close box" that's greeen & polka-dotted that you
need to hit control-twaddle-double-bucky-left-mouse to activate, but from
the application's point of view, you've still just hit the "close box".
How much do the applications programs assume about the particular
_implementation_ of the user interface?  (not very much I hope)

If you have shared libraries, this might be practical.  A customizable but
still compatible user interface.

>-- 
>Avadis Tevanian, Jr.    (Avie)
>Chief Operating System Scientist
>NeXT, Inc.
>avie@cs.cmu.edu or avie@NeXT.com
>-- 

Matt Kennel
mbkennel@phoenix.princeton.edu