Toggle between point to point and generic 6dof constraint for mouse picking in the demos
Use a 'equal vertex thresdhold' in the btVoronoiSimplexSolver of 0.0001f by default.
This can be disabled (or configured) using defaultCollisionConfiguration->getSimplexSolver()->setEqualVertexThreshold(0.f);
See http://code.google.com/p/bullet/issues/detail?id=305