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

[Artur Malabarba]

Hi Alan,

2015-11-02 15:44 GMT+00:00 Alan Mackenzie <acm@muc.de>:
> So how about us just moving all these checks to where they really
> belong, in isearch-lazy-highlight-update?  I've a feeling that if we do
> this, then your function follow--search-function becomes unneeded.

Yes, I think this might work too. And I like the idea of eliminating a
redisplay inside the command-loop.
Could you test it?

You'll probably still need a simpler version of that
follow--search-function to ensure that lazy-highlighting extends to
all windows (instead of stopping inside the selected-window), but at
least it won't need that `select-window' part that you said is bad.
:-)

>> Matches are highlighted on all windows
>
> Here, the matches should be highlighted on all the windows in the FM
> group without exception.  I think a new option you're providing allows
> lazy highlighting to happen only in the current window.  This is a bad
> idea when FM is active.

No, currently lazy highlighting to happens only in the current window
(with or without follow-mode). This happens for 2 reasons. (1) Isearch
only highlights between window-start and window-end, and (2) isearch
limits the highlithing overlays to only be displayed on the selected
window.

The new option I introduced to isearch allows the highlighting
overlays to be displayed on all windows (solving (2)). Furthermore,
one of features of that follow--search-function function is to make
sure that highlighting doesn't stop `window-end' (solving (1)).