The bug that we found in RTTPicker is connected to resize event.
After any resize RTTPicker stops working properly, it always returns onMiss() method.
As far as we understood the initial image to calculate intersections in RTTPicker has size of 256.
While doing resize this image is forced to take the form of viewport (it is also resized).
This happens somewhere inside OSG, because it is set to FRAME_BUFFER_OBJECT.
For our solution we changed line 243 in RTTPicker.cpp: