This class extends LocatableNodeController with an association
with a configuration. The configuration is central to a Ptolemy GUI,
and is used by derived classes to perform various functions such as
opening models or their documentation. The class also contains an
inner class the specifically supports accessing the documentation for
a Ptolemy II object.
Set the configuration. This is used in derived classes to
to open files (such as documentation). The configuration is
is important because it keeps track of which files are already
open and ensures that there is only one editor operating on the
file at any one time.