Alexei
I discovered the same thing on my version of the toolbar. I saw that Unity had renamed the “VisualElement” that allows injection, but even after changing it to the new...
No worries! I'm having the same problem and I'm working on it right now, but for the moment I don't have any more help to offer, and I even think...
@nnra6864 Find a workaround described in the end here https://github.com/Alaxxxx/CustomToolbar/issues/12 I don't use the new API as it is too restrictive for now, but this workaround works, it is easy...