In a scene using an object picker while the Scene3D is inside a Dialog, the picking is done with an offset.

Capturing a click on an object requires to click to the left and over the actual object. The observed offset is proportional to the thickness of the boundary of the dialog. Its position in X and Y seem to have an effect too as if a translation between the top left corner of the window and the Scene3D is ignored. If this offset get too large, it seem to wrap around as well. Putting the Scene3D outside the dialog works fine.