`alignmentgroup` & `offsetgroup` restyle bug

    @archmoj this looks great! There's one piece I don't understand: if I load `zz-scatter-grouping-vs-defaults`, then clear all the `alignmentgroup` attrs - `Plotly.restyle(gd,'alignmentgroup',null)` - then the traces in the upper right subplot disappear. They also disappear if I set the `alignmentgroup` for just those two traces to `'bottom'` to match the ones below - `Plotly.restyle(gd,'alignmentgroup','bottom', [3,9])`.

If I also clear offsetgroup they come back, and if I set the offsetgroup for those two to something explicit they get their own group.

So I guess the odd case is when alignmentgroup is either all null or all the same but one trace, in a different subplot from the others, doesn't have an offsetgroup.

There's a related case that's clearly broken: in the same mock, if I just clear offsetgroup for the last trace it stays where it was. But if I first give it a new offsetgroup (so it correctly gets new space) and THEN clear it, it gets pushed into the next group!

Plotly.restyle(gd, 'offsetgroup', null, 11) // clear the group for the last trace, this is OK

Plotly.restyle(gd, 'offsetgroup', '3', 11) // put it in a new group
Plotly.restyle(gd, 'offsetgroup', null, 11) // clear its group

I don't think this is unique to scatter, I can get a similar history-dependent errors from bars from setting / clearing the offsetgroup of the FIRST bar in the bottom right subplot (ie replace the 11 with 4 in those commands). Maybe we just treat null as its own offsetgroup if there are other traces with an offsetgroup on the same axis?

Originally posted by @alexcjohnson in https://github.com/plotly/plotly.js/issues/6381#issuecomment-1360562317

Tái hiện vấn đề trong mock zz-scatter-grouping-vs-defaults bằng các lệnh gọi Plotly.restyle đã mô tả cho alignmentgroup và offsetgroup, bao gồm cả việc xóa và gán nhóm. Truy vết hành vi nhóm từ các điểm vào đó. Được xem là hoàn thành khi việc xóa hoặc thay đổi nhóm không khiến các trace biến mất, bị đẩy sang nhóm khác hoặc phụ thuộc vào thứ tự của các restyle.