I'm not actually sure if this is supported on the WPF side, but when we move a type to a namespace (via that UI, or via sync namespace/folder structure), it'd be great if we could IVsRefactorNotify of that "rename" such that WPF can pick up on it and change the namespace for just that type.

Note, if you rename an entire namespace, IVsRefactorNotify works as expected. But this would be a different scenario that perhaps WPF wasn't expecting.