||A class that contains information about what capabilities a property in a
Theme can have,
which class type, max value, min value, if
null is OK, and so on.
||A abstract base class for all themes.
||A key in a com.miginfocom.theme that denotes a link to another key's value rather than providing its own value.
Is a wrapper of a the key and contains no processing of its own.
||Handles loading and saving of themes and is a container for looking up themes with a context.