bug#21380: 25.0.50; GTK-induced segfault when scheduling timer from window-configuration-change-hook

[Eli Zaretskii]

> Date: Sun, 30 Aug 2015 16:42:21 +0000
> From: Pip Cet <pipcet@gmail.com>
> Cc: 21380@debbugs.gnu.org
> 
>     > Does that make sense to you?
>     
>     It does, but there's one additional factor that was supposed to
>     prevent such problems: the first thing timer_check does is copy
>     Vtimer_list to a local variable; then it works on that copy. So
>     whatever happens in the meantime to Vtimer_list should not have
>     affected concat, because concat is called on a copy.
> 
> I'm not sure I understand. This issue is happening while the temporary copy is
> being created, not afterwards, IIUC.

Then all we have to do is block QUIT during that copy, no?