Event Bubbling through Layers

I am trying to get events to fire on a rectangle that is partially
hidden below a second rectangle. I want to be able to mouseover the
lower rectangle in the area that is covered by the upper rect. and
still have the mouseover event fire. Is this at all possible in
Firefox, SVG, without grouping the objects with a <g> tag?

I understand that SVG uses the standard event bubbling model that is
based on xml tag hierarchy. What about z-index / layer hierarchy -
where objects share an x-y coordinate but on is on top of the other?
It appears that only the highest z-index object will have its events
triggered on, for example, a mouseover event. Is this correct?

Thanks!