QGLSceneNode::draw should execute painter.setPickObjectId with / without having geometry

Hi,

I am encountering a problem of picking.
I create a pick node for a QGLSphere node. However, the signal is never triggered.
After tracing the problem, I realized the painter.setPickObjectId only being executed if the node has geometry.
However, if I want to group multiple meshes together as one picking node, original implementation will against the case.
A workaround solution is uploaded as an attachment but a more permanent solution will be much appreciated.