I've created a diagram with simple shapes joined by NLineShapes connectors. The shapes each have a NShowHideSubtreeDecorator to allow child shapes to be collapsed.

If one of the line connectors between shapes overlaps or is near to the +/- shape of the decorator, I find that I cannot get the decorator expand/collapse action to fire. I'm guessing this is due to the connector line being above the decorator in the drawing z-order?

Any suggestions on how to keep the decorator on top?
Thanks
Andy