Improve grouping

[cenfun]

Can we add more groups like left hand/right hand/face, just grouped so that it can be found easily, maybe it doesn't have grouping behavior just grouping, and when the group is collapsed, the scrollbar is smaller. Thanks.

[huchenlei]

I don't think it would be better to introduce more nested structure here. From my personal experience, I spend very little time on that list structure. It is only used if I want to know what the keypoint correspond to or I want to make an invisible keypoint visible again.

I would reconsider this if more users report the same issue.