cycling through items on a canvas?

["Johan Kohler" <johan kohler gmail com>]

Hi,
I add items to the root group of a canvas using repeated calls like:
polygon_ = manage(new CRenderPolygon(*root(), points_));
where CRenderPolygon is derived from Canvas::Polygon.  I always reuse
the same pointer polygon_.  Now I want to test whether a point is in
any of the polygons.  How can I get an iterator or something over all
the existing items on the canvas so that I can access them in turn?
Should I rather push the pointers into a vector  perhaps?

Thanks,
Johan