[lukeo05]

This is only true for DOM components, e.g. an <input> component, which can't have a onWindowShow() method associated with it.

Customer components, e.g. an <MyInput> component that wraps a DOM <input> and provides custom onWindowShow() functionality are unaffected.

[skrebbel]

Ahhhh of course! OK that makes a lot of sense. Actually, it makes is more uniform: a ref has whatever properties and methods that ref could possibly expose - be it a "built-in" component (aka a DOM element) or a custom one. Nice!