button press events missing on gnome canvas items

Is there a trick to it?  I reported a bug at
http://bugzilla.gnome.org/show_bug.cgi?id=162326 but I'm sure it can't have
been overlooked.

My code looks like this:

View inherits from Bakery::View and Gnome::Canvas::Canvas
Node inherits from Gnome::Canvas::Group and contains a pixbuf and text

I can add and remove Nodes from the View with no problems, they display as
expected.

The signal handler in Node, Node::on_event, receives all the simulated
events from the Canvas, bar button press events.  This behaviour surprised
me and for a while I hacked around it by moving the button press handler
into the canvas itself; but as Canvas::get_item_at() returns an Item*, the
only way to call the right methods in Node is to dynamic_cast it, which
feels dirty :-)

So I'm wondering if there's a trick to it.  The only other post I can find
about this problem is
http://mail.gnome.org/archives/gtkmm-list/2004-July/msg00083.html but the
recommended workaround is impossible as I described in the bug report.

So, ideas?  Is it impossible for a Group to receive button press events,
even though it gets button release, motion notify, enter, exit and even
focus change events?  If so should I instead be binding my handler to the
pixbuf and text's own signals?

Thanks