bug#61704: 29.0.60; Crash in get_narrowed_begv

[martin rudalics]

> I maintain that the bug is (was) most probably not in get_narrowed_*.
> I just built Emacs with the GTK, Lucid and no toolkits, I disabled
> everything (tool-bar, menu-bar, scroll-bar, fringe-mode 0), and even
> with that, after resizing the Emacs frame until it is literally a
> single pixel on screen, I'm not able to get (under emacs -Q) a window
> width or a height equal to 0 there.  The smallest values I get are
> width = 2 and height = 1.

What you listed above is not likely to affect the height of a window -
it's the header, mode and tab lines that count more.

> That, the fact that this code has been there for a half year without a
> single reported crash (if resizing a window is enough to trigger such
> a crash, that would surely have happened already), and the fact that
> get_narrowed_* is not executed at all in the ediff control frame,
> means that there is a bug somewhere else.

Don't worry.  What Po Lu saw is something I've seen in different forms
much earlier.  Small frames can be a problem for redisplay.

martin