The Extensible interface is implemented by a Java Control implementation class if the
control defines an extensibility model that allows extended operations to be declared
using a JCX interface.
The interface provides the invoke method, that is called whenever an
extended operation is called by the client at run time.
Called by the Controls runtime to handle calls to methods of an
extensible control.
Parameters: method - The extended operation that was called. Parameters: args - Parameters of the operation. The value that should be returned by the operation. throws: java.lang.Throwable - any exception declared on the extended operation may bethrown. If a checked exception is thrown from the implementation that is not declaredon the original interface, it will be wrapped in a ControlException.