What do you think about adding a NamedValueSet for holding properties to the LookAndFeel class, pretty much like the Component class already has?
For reasons that are quite long to explain there, I would find it very convenient to store additional informations about the LookAndFeel itself without having to derive a class for just that, for example the default sizes for knobs, or the position of their center (these are very useful informations when the widgets need to be repositioned in resized() methods)