Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!rutgers!bellcore!texbell!sugar!ficc!peter
From: peter@ficc.uu.net (Peter da Silva)
Newsgroups: comp.windows.x
Subject: Re: Contents of windows
Message-ID: <3985@ficc.uu.net>
Date: 26 Apr 89 14:22:19 GMT
References: <8904251538.AA00185@devnull.sun.com>
Organization: Xenix Support
Lines: 37

In article <8904251538.AA00185@devnull.sun.com>, dshr@SUN.COM (David Rosenthal) writes:
> There is no escape.  It is a fundamental requirement of X that the client
> respond to Expose events by re-painting the exposed area.  If you don't
> like this requirement,  go find yourself some other window system.  This
> requirement is one of the reasons why X is simple and portable to a wide
> range of displays,  so the other window system you find is not likely
> to be as widespread or successful as X.

Now I may be dim, but I don't see how the lack of a guaranteed backing store
leads to the increased portability of X. One might as well say that the ability
to operate without a mouse leads to the increased portability of Microsoft
Windows (yes, Windows works quite well without a mouse). If the display server
doesn't have a backing store it can be emulated in the client library, though
I find it hard to imagine a hardware system that can support X that doesn't
have memory to burn.

I've worked with a windowing system that gives you the option of using or not
using a reliable backing store. The performance enhancement having such a
resource is considerable, as is the degree to which it simplifies the job of
programming. I just started working on an X machine, and all the disadvantages
of working without a backing store are painfully evident in this display. Every
expose event is followed by agonizing widget-by-widget repaints.

Think of a backing-store as curses for your server. Or do you really prefer
working directly with termlib?

Backing up:

> If you don't like this requirement,  go find yourself some other window
> system.

I'd love to. X is the Fortran of windowing.
-- 
Peter da Silva, Xenix Support, Ferranti International Controls Corporation.

Business: uunet.uu.net!ficc!peter, peter@ficc.uu.net, +1 713 274 5180.
Personal: ...!texbell!sugar!peter, peter@sugar.hackercorp.com.