I have tried to implement this but am just not quite getting it...

In the editor, I want an easy way to select a shape that is underneath the current shape - but I don't want to send the current shape behind.

Let me give an example to try to better explain.

I have a circle on a diagram. Above it is a triangle, and above that is a rectangle.

The first click would select the rectangle so I could edit its properties.
I could then click in the same location to select the next shape below it - in this case the triangle.
I could then click again in the same location to select the next shape below that - the circle.

I want to preserve their Z-Order in the end diagram, I just want to edit the circle's properties without moving the shapes above it (or changing their Z-orders.)

Is this easily done?