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From: John Morey <jmorey@tbi.com>
Subject: Re: scrollbars 
To: cthomp@xemacs.org (Chuck Thompson)
Date: Tue, 7 Jan 97 21:21:47 EST
Cc: xemacs-beta@xemacs.org
In-Reply-To: <199701080122.TAA07173@xemacs.cs.uiuc.edu>; from "Chuck Thompson" at Jan 07, 97 7:22 pm
Mailer: Elm [revision: 70.85.2.1]

> 
>     Greg> Something that's always bugged me is that it seems the size
>     Greg> of the scrollbar and the scrolling are based on character
>     Greg> positions instead of lines.
> 
> Emacs / XEmacs is not a line based editor.  Period.  If it was
> scrollbars would have never been anything but line based in the first
> place.  Probably.
> 
> It is actually fairly easily to implement (at first look) if you
> either don't care about performance or run XEmacs on a Cray.  It is
> not quite as trivial as it looks at a glance since they should really
> be based on the number of display lines, not the number of newlines.

I do not agree with this.  IMHO, the scroll bar size should be based
on the the pixel size of the display area of the frame divided by
the pixel size of the entire buffer (% of buffer height displayed).

Again IMHO. The scroll bar should NOT change size as the buffer is
scrolled up and down which could be the case if the scrool bar is
based % of lines displayed or % of characters displayed.

> With variable height lines and variable width characters that becomes
> difficult to do.  Something like the Motif text widget is easy.  Keep
> a running count of the number of lines and an additional counter which
> is incremented for each line wrap which is always easily calculatable
> since it is always caused by the same number of characters.
> 
> 
> 			-Chuck
> 

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