bug#53420: 29.0.50; NULL cairo context while frame resize, causes segfault with visible-bell

[Po Lu]

Antonio Carzaniga <antonio.carzaniga@usi.ch> writes:

> M-x set-variable RET visible-bell
>
> Now resize the emacs frame and at the same time give a keyboard command
> that causes emacs to ring the bell.  I know it's not a common thing to
> do, in fact I just happened to do that by mistake.  Specifically for me,
> s-<up> maximizes the frame vertically, and I also pressed <down>, which
> causes emacs to complain that s-<down> is undefined and therefore ring
> the bell.
>
> Anyway, now emacs crashes.  A bit of analysis reveals the following
> sequence of events (logged using gdb) in which the cairo context
> associated with the selected frame is temporarily set to null during the
> frame-resize operation, and pgtk_ring_bell and then pgtk_flash are
> called before the cairo context is properly restored.

Thanks, should be fixed now.