An application I am working on has an object derived from Gnome::Canvas::Canvas,
and contains some objects derived from Gnome::Canvas::Pixbuf; I set a signal
handler in the Pixbuf-derived object, and I can see that it receives all events
except Gdk::BUTTON_PRESS_EVENT (i.e. ENTER and LEAVE_NOTIFY, MOUSE_MOTION and
even BUTTON_RELEASE).

Google searching results in only this other post describing the same problem:

http://mail.gnome.org/archives/gtkmm-list/2004-July/msg00083.html

Unfortunately, the recommended answer presented in that thread, use 'add_events'
to make sure that the event mask is set correctly, doesn't work because
Canvas::Item doesn't derive from Gtk::Widget, it derives directly from Gtk::Object.

The expected behaviour is that Canvas::Item s also receive the BUTTON_PRESS
event; currently my workaround is to move the item signal handler into the
canvas itself and special case a button press event that is also over an Item,
which is an inelegant solution.

Interestingly, the canvas_events.cc example from the libgnomecanvasmm module
(i.e. via viewcvs on cvs.gnome.org) (when the sigc::slot functino calls are
replaced with sigc::mem_fun so that it actually compiles) does respond to button
press events on the items, but with as far as I can tell identical code I can't
reproduce that (correct) behaviour.

I'm using libgnomecanvasmm-2.6 and related libraries as packaged in Ubuntu
Warty.  Marking as severity "major" because the behaviour suggests that the
implementation is incomplete.