bug#15045: Point jumps inappropriately around time of Semantic lexing

[David Engster]

Eli Zaretskii writes:
>> From: David Engster <deng@randomsample.de>
>> Yes. But it shows that this bug is easy to make, and it's hard to track
>> down.
>
> It is also very rare.

I don't think the bug is rare. I do think that this bug being triggered
is rare, since we don't have many non-idle timers in Emacs that trigger
redisplay (are there others in Emacs core besides the display-time event
handler?). It might be fun to work for a while with a dummy timer which
triggers redisplay once a second or so.

I also think this bug is seldomly reported because it's impossible to
give a recipe if you don't know that it is a timer that triggers it
(which is why I never bothered to report the bug in speck-mode).

-David