Bug 126839 [DataBinding] IObservable refactoring
bundles/org.eclipse.jface.databinding/src/org/eclipse/jface/internal/provisional/databinding/IDataBindingContext.java
* 
	 * @param targetDescription
	 * @param modelDescription
	 * @param bindSpec
	 *            the bind spec, or null
	 * @return The IBinding that manages this data flow
	 */
	public IBinding bind(Object targetDescription, Object modelDescription,
			IBindSpec bindSpec) ;
	/**
	 * Creates an updatable object from a description. Description objects are
	 * interpreted by implementors of IUpdatableFactory, the data binding
	 * framework does not impose any semantics on them.
	 * 
	 * @param description
	 * @return IUpdatable for the given description
	 */
	public IUpdatable createUpdatable(Object description);
	/**
	 * Tries to create a validator that can validate values of type fromType.
	 * Returns <code>null</code> if no validator could be created. Either
	 * toType or modelDescription can be <code>null</code>, but not both. The
	 * implementation of this method will iterate over the registered bind
	 * support factories in reverse order, passing the given arguments to
	 * {@link IBindSupportFactory#createValidator(Class, Class, Object)}. The
	 * first non-null validator will be returned. 
	 * @param fromType
	 * @param toType
	 * @param modelDescription
	 * @return an IValidator, or <code>null</code> if unsuccessful