bug#8874: Redisplay confusion in Info, due to recentering fix

[Eli Zaretskii]

> From: Chong Yidong <cyd@stupidchicken.com>
> Cc: 8874@debbugs.gnu.org
> Date: Sat, 18 Jun 2011 14:07:10 -0400
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> > How urgent is it to fix this?  Can it be postponed until I'm done with
> > bidi reordering of display strings, and we enter code freeze?
> 
> The bidi work is more urgent, so feel free to postphone the fix for this
> until you have the time.
> 
> FWIW, I took a quick look, and it appears that the following should do
> the trick.  But it can wait till you have time to double-check the code.

The problem was with the header line that Info uses by default, and
which was not accounted for when computing the new window start
position.  (If you set Info-use-header-line to nil, the bug goes
away.)

I fixed (in trunk revision 105541) the calculation of the window start
to account for the header line when it's present, and that solves the
bug.

Thanks.