Subject: bug#17453: Isearch doesn't work properly with Follow Mode.

From: Alan Mackenzie <[email-masked]>
Date: Sat, 31 Oct 2015 23:56:51 +0000

Hello, Juri.

On Sun, Nov 01, 2015 at 01:35:53AM +0200, Juri Linkov wrote:
> > If Follow Mode is not enabled, all the above functions do the Right
> > Thing on the single window.

> >>From another perspective, settings lazy-highlight-buffer to t
> (implemented in bug#21092) and removing the current restriction of
> (overlay-put ov 'window (selected-window)) will lazy-highlight matches
> in all follow windows with no effort.

I wasn't actually aware of that fix.

There were three main problems my patch fixed:
1) Searching commands were restricted to a single follow window.  This
was caused by the lazy highlighting mechanism, as you say.
2) Lazy highlighting was only being done in a single window.
3) In scrolling commands, point was restricted to the singled window,
rather than being able to move freely throughout all the windows.

There were also some subtle things which could go wrong, in particular
when the current isearch match spans two windows, and the next command
causes the echo area to expand a line.  This caused spurious scrolling
of the windows.

-- 
Alan Mackenzie (Nuremberg, Germany).