Tim, I understand that you are a bit of a perfectionist, and that's very good :-) But here you want to "fix" a bug that no one reported, and that breaks a completely weird use-case that never actually worked (why would want to have additional margin below the header, that could not be implemented with a margin in the content item?), and by doing so you are changing a well documented behaviour that was working, that at least one developer is using, and for which there isn't a perfect workaround.
Tim, I understand that you are a bit of a perfectionist, and that's very good :-) But here you want to "fix" a bug that no one reported, and that breaks a completely weird use-case that never actually worked (why would want to have additional margin below the header, that could not be implemented with a margin in the content item?), and by doing so you are changing a well documented behaviour that was working, that at least one developer is using, and for which there isn't a perfect workaround.
That's all for the sake of API perfection?
That's not how a toolkit should work.