Not sure if I am doing something wrong here but here we go:

I tried to make use of the oneview enabled with default settings. Using only the 3d perspective view to draw some curves, if I constrain the angle of the curve, Hold shift to find the 45 angle and the hit tab in order to lock the direction, my curve does not line up with my starting point which is already aligned on my current plane.

As an example, from a right construction plane, I have my first point at X0,Y0,Z0 and extending the curve along the Y and Z axis (for the 45 degrees), the X does not remain 0 but gets below 0.

Has anyone else noticed this?