The key snooper functions installed by Gtk2->key_snooper_install could helpfully trap errors through the Glib->install_exception_handler funcs.  The program below shows how an error in a snooper terminates the whole program.

(A snooper of course is basically an event handler like widget event handlers, but encompassing all widgets, and on that basis will almost certainly want to continue the main loop.)


use strict;
use warnings;
use Gtk2 '-init';

Glib->install_exception_handler (sub {
                                   print "exception trapped\n";
                                   return 1;
                                 });
Gtk2->key_snooper_install (sub {
                             print "key snooper runs\n";
                             die "now throw an error";
                           });
my $toplevel = Gtk2::Window->new ('toplevel');
$toplevel->add (Gtk2::Label->new('Press any key'));
$toplevel->show_all;
Gtk2->main;