[11 Nightly] :nth-last-child(1) Only evaluated once at runtime

[Mrcubix]

Discussed in AvaloniaUI/Avalonia#12147

^{Originally posted by Mrcubix July 11, 2023}
For some reasons, the selector :nth-last-child(1) seems to only be evaluated properly at first, any additions done after the Window is shown will result in an incorrect behavior.

in this exemple, the last element is supposed to have a margin of 0, so that the scrollbar doesn't show up until another element is added.

the same behavior can be obtained using this repo: https://github.com/Mrcubix/Avalonia-Last-Nth-Child-Selector-Issue

Note that the orginal discussion was written in an earlier version, but the issue is still valid to this day

about the same styling works for ItemsControl, however, ItemsControl suffer from a worse issue explained here #12137

[timunie]

@Mrcubix can you test AvaloniaUI/Avalonia#13770 ? should be in latest nightly

[Mrcubix]

Will do tomorrow

[Mrcubix]

Still broken in the reproducible repo, even more broken than it used to be.

All last or used to be last elements now keep their nth-last-child class even after a new one is added, and that, is for a simple case.

[timunie]

That's actually good news. It means it has now a logic we can follow and we know where in code to digg. 🙂