refptr and this

[Jonathon Jongsma <jonathon quotidian org>]

I've run into an issue while playing around with goocanvasmm trying to
implement custom items and I'm wondering if anybody has run into this
before.  The issue is as follows:
- To create a 'group' item, you need to implement the add_child virtual
function
- within the add_child virtual function, it appears that you are
supposed to call set_parent on the new child and set its parent to
yourself.  In other words, something like:

add_child_vfunc(Glib::RefPtr<Item> child, int position) {
 // add child to an array of items
 child->set_parent(this);
}

The problem is, the set_parent() function takes a Glib::RefPtr<>, so I
would need to do something like
 child->set_parent(Glib::RefPtr<Item>(this));
Except this seems to cause refcounting problems and the program crashes.

I can obviously revert to the C API and do something like:
goo_canvas_item_set_parent (child->gobj (), GOO_CANVAS_ITEM(gobj ()));
But it would be nice not to have to do that.  Any ideas?

For reference, the C function goo_canvas_item_set_parent() does not take
a reference on the parent object...
-- 
Jonner