missing button release event?

[Paul Emsley <paul emsley bioch ox ac uk>]

Hi,

When I create a goocanvas

   GtkWidget *canvas = goo_canvas_new();
   GooCanvas *gc = GOO_CANVAS(canvas);

I then attached callbacks to it...

      ... other callbacks ...
      g_signal_connect(G_OBJECT(goo_canvas_get_root_item(gc)),
               "button_release_event",
               G_CALLBACK(on_canvas_button_release), NULL);

  This works fine almost all the time - however, there is one operation 
(a line addition) where the on_canvas_button_release callback doesn't 
get called (I added a print statement in it to check).  I can't think 
why it might not be being called.  Can you help?

Cheers,

Paul.

p.s. code here: http://coot.googlecode.com/svn/trunk/lbg/lbg.cc