Ref https://github.com/webstudio-is/webstudio/issues/3399
What to test
- hover
- select
- hiding (with show button) item should be transparent
- slot should be purple
- hide slot fragment
- render collections
- enter should trigger edit instance text
- support editing instance label with cmd+e
- should prevent dragging rich text child
- should prevent dragging non detachable instances (accordion header)
- should support reparenting after the last child