bug#14582: 24.3.50.1; Strange overlay behavior, when window-start is inside an overlay.

[Michael Heerdegen]

Eli Zaretskii <eliz@gnu.org> writes:

> Basically, we are being asked to introduce application-level logic
> into the general-purpose parts of the display code: the application
> sets the window-start at some place which happens to be a bad idea,
> and wants the display engine to save the application from itself.  I
> don't think it's TRT.

There is a misunderstanding here: hideshow doesn't change window-start.

What actually happens is: Elisp, be it hideshow or whatever, changes
visibility of some part(s) of the buffer.  Sometimes it can happen that
the old window start position (in any window) is part of a fold
(invisible region) afterwards.  Then the issue I described occurs.

Michael.