Ehh, not perfect. If the user clicks out of the cell but in the listview, the edited signal will fire twice (once normally, once thanks to the hackery above).

Modified version:

package Gtk2::CellRendererTextThatIsNotCompletelyUseless;

use Glib::Object::Subclass "Gtk2::CellRendererText";

sub START_EDITING {
    my ($self, $event, $view, $pathstr, $back_rect, $cell_rect, $flags
+) = @_;

    my $entry = shift->SUPER::START_EDITING(@_);

    $self->signal_handler_disconnect($self->{bad_hack}) if exists $sel
+f->{bad_hack};

    $self->{bad_hack} = $self->signal_connect(
      'editing-canceled' => sub {
         my ( $event_box, $event ) = @_;
         $self->signal_emit( edited => $pathstr,   $entry->get_text() 
+);
         return 0;
      }
   );

    return $entry;
}
[download]

The appropriately named bad_hack abuse is needed to avoid connecting the signal handler again and again - but we can't just install it once and leave it be, because the anonymous sub closes over $entry, which refers to the Gtk2::Entry that is destroyed and recreated every time the user starts editing, so the need a new handler with a new closure of the newly created $entry every time.

I feel a slight sting that there is a better way to do this, I just don't see it.