From xemacs-m  Thu Aug 14 15:07:57 1997
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Date: Thu, 14 Aug 1997 16:07:47 -0400 (EDT)
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From: Kyle Jones <kyle_jones@wonderworks.com>
To: xemacs-beta@xemacs.org
Subject: Re: scrollbar arrow gets stuck down, buffer scrolls by itself
In-Reply-To: <m2hgctfqfj.fsf@altair.xemacs.org>
References: <87afimndpv.fsf@bittersweet.inetarena.com>
	<m2hgctfqfj.fsf@altair.xemacs.org>
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SL Baur writes:
 > Karl M Hegbloom <karlheg@inetarena.com> writes:
 > 
 > > Also, the tops of the 'foreign' (non-Oregonian) characters are left
 > > behind when you scroll.  They go away if you trigger refresh or wipe
 > > with another window.  Is that an off-by-one bug?
 > 
 > Those are Redisplay Goobers(TM) relating to variably sized fonts in
 > use in the same buffer.  Perhaps Joel Peterson's work in redisplay
 > will cure them.

I believe the real cause is that the fonts are crocked in that
the accented and italic glyphs extend outside their bounding box.
So painting an empty box doesn't erase the part that extends
outside.  The only way to cleanly erase them is to repaint the
glyph with the background color.  But since the glyph extend
outside its box, doing that might take a chip out of some other
object on-screen.

