Alpha sorting was a long-standing 'problem' but it will be fixed in 2.8.
This has been reported a couple of times, see T43093, T51964, T46349, T49376, T44826, T41731

uploaded the wrong file... use this one instead{F3398841}

Anti-aliasing happens from the outside side of the spline, which is actually happened to be an inner side of your "buggy" spline. Just switch direction of the spline and anti-alias will work fine.

Sorry, I've been away and haven't had time to update this. I'm attaching a file demonstrating the problem.

Report has not been reacted on for 7 days, closing due to bug tracker policy.

Thanks for the report, please provide a blend file for testing.

Can confirm the issue, 'Add Square' and then select a mask point, and the id_type of points' parents remains to 0.

Before creating another bug of this kind, here is another:

Sorry, I didn't know that the file wasn't ever uploaded. Here it is:

This file is created from scratch in 2.78a.

This file is somewhat corrupted: mask parent's ID type is supposed to always be ID_MC (ID type of MovieClip), but in this file the type is simply 0 (which is not a valid ID type even).

Could you check with latest master (i.e. buildbot builds)? IIRC, sergey committed a fix for this sometime in the past few weeks-month.

Cannot confirm this, would bet you somehow disabled Global Undo in UserPreferences, Editing settings…

I can't really reproduce the issue. Please test if latest builds from builder.blender.org still have it and if they do please attach .blend file which demonstrates the issue.

Awesome bug :)

One week without response.

Most likely same issue as in T48422, please tray again with latest testbuild, should be fixed.

One problem remains though: Currently(in master) you are able to adjust the newly created handles manually by keeping your mouse button pressed and moving your cursor. With this patch this cannot be done anymore because it calculates the handles for you.