mstr2

> If this PR goes forward, it will need a CSR, since it does impact source code compatibility. As you point out, you can't usefully extend Node today, since you...

> > The fact that you can't extend `Node` is a system invariant > > But I **can**, and the code provided above runs with no exception - in either...

> can you point me to where it says one can't extend Node or that it is verboten? https://github.com/openjdk/jfx/blob/4647367ce4590440fbb85675055225c869502314/modules/javafx.graphics/src/main/java/com/sun/javafx/scene/NodeHelper.java#L81

> "should" and "may" are not the same as "must" and "will". I think this is just suboptimal language, and not a material distinction. You _will_ get a runtime error...

> If this goes forward, please seal `Material` as well. If we seal `Material`, we should probably also seal `Paint`. What do you think?

> I don't see why they are related, but if `Paint` can't be subclassed then I don't see a reason not to seal it. I can envision possibilities to create...

/integrate