(*) Should pivot.wtk.Dimensions/Insets/CornerRadii/Bounds be final and immutable? In theory, with proper escape-analysis and/or stack-allocation newer JDK's will be able to optimise more with immutable data-structures. But then current style is easier to code against. But then we could perhaps fix that with some utility methods (e.g. Dimensions max(Dimension other)).
(*) What does HorizontalAlignment.JUSTIFY and VerticalAlignment.JUSTIFY mean? I also note that it only seems to mean something to FlowPane and Form - perhaps we should add IllegalArgumentException to other places so that people don't accidentally set it on other components? (*) Why does Renderer#getStyles not return a StyleDictionary? seems like it would be nice if Style information was available in a generic fashion. (*) TabPane would be more useful if I could set a component on the title section of the tab, so I could draw whatever I wanted. (*) Component#StyleDictionary should expose methods for getting the valid values of an enum property, since some methods will take an enum, but will only be valid for some subset of the values on that enum (e.g. usage of VerticalAlignment) (*) The Component#Attributes mechanism looks fragile. What if I want to extend TabPane and add my own attributes? It seems like this mechanism could be less fragile and more type-safe by hand-coding Maps into the relevant sub-classes.
