Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!swrinde!zaphod.mps.ohio-state.edu!brutus.cs.uiuc.edu!lll-winken!decwrl!decwrl.dec.com!joel
From: joel@decwrl.dec.com (Joel McCormack)
Newsgroups: comp.windows.x
Subject: Re: 32K pixel limit on viewport/list widget??
Keywords: list, viewport, Xaw, X11R4
Message-ID: <2736@bacchus.dec.com>
Date: 12 Feb 90 19:16:06 GMT
References: <1990Feb12.162019.4239@ux1.cso.uiuc.edu>
Sender: news@decwrl.dec.com
Reply-To: joel@decwrl.dec.com (Joel McCormack)
Organization: DEC Western Research Laboratory
Lines: 10

You are looking at the fundamental limitation of the protocol to a
16-bit (signed) address space.  X and y coordinates are limited to the
range [-32768..32767].  A scrolling mechanism can hit this limit rather
easily if attempts to hide all scrolling activities by giving the
scrollee a huge window in which to paint.

The correct way to do things, though not the easiest, is to avoid the
use of viewports to accomplish scrolling.

- Joel McCormack (decwrl!joel, joel@decwrl.dec.com)