I've never used gtk2 or anything like that, but this is just screaming out for closures. :-) It'd help people like me help you if you showed the code you had, though. I'm stealing code from Gnome2::Canvas's docs.

my $box = Gnome2::Canvas::Item->new ($root, 'Gnome2::Canvas::Rect',
                                     x1 => 10, y1 => 5,
                                     x2 => 150, y2 => 135,
                                     fill_color => 'red',
                                     outline_color => 'black');
$box->lower_to_bottom;
$box->signal_connect (event => sub {
        my ($item, $event) = @_;
        warn "event ".$event->type." on $box\n";
});
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The key is to simply use $box, or whatever, in the anonymous subroutine, and it will be forever linked to that instantiation. Even if you create a bunch of different $box's in a loop or in another subroutine, the $box it refers to will always be the correct one.