The new version of Bezier Toolkit - 0.9.52 - with the Snapping & Locking framework is now available for download. You can now snap and lock to plane, axis and more with all three Flexi tools.
And there are a number of other options, that would make working with curves fun 
For precision drawing and editing, it’s now also possible to enter (or tweak) location values via keyboard (even in polar coordinate form! ).
Review video: https://youtu.be/VQCXZbOq47s
And yes, the tools now work in all views, including the quad view
Please let me know if you face any issues or come across defects.