@Sergey Sharybin (sergey), I guess that one is for you? ;)

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.