proposal was to add another special init hack for the viewer node->id, but rather would do it right and so moved all the special init hacks for constant ID backpointers (Scene for RenderLayer, Composite, Defocus, FileOutput and MovieClip for MovieClip, MovieDistortion and Stabilization nodes). These are now part of the local init callbacks functions of the appropriate nodes, using the new initfunc_api callback which takes a Context pointer, so they have access to Scene.