Bug 118429 [DataBinding] Validation should use IStatus, not just Strings
In order to use data binding in Workbench or IDE dialogs and preference pages, we need validation in terms of IStatus objects. Using strings is too simplistic. For example, look at the wizard for creating a new class. You will get a warning if the class name does not start with an uppercase letter, or if you don't provide a package name, but you will still be able to click "Finish" to proceed anyway. (Note that IStatus is currently not on the classpath, we need to re-introduce the dependency on org.eclipse.equinox.common, which contains IStatus etc.)
bundles/org.eclipse.core.databinding/src/org/eclipse/core/databinding/BindingEvent.java
}
	/**
	 * The model observable for the change that is being processed.
	 */
	public final IObservable model;
	/**
	 * The target observable for the change that is being processed.
	 */
	public final IObservable target;
	
	/**
	 * The diff describing the change, or <code>null</code> if no diff is
	 * available.
	 */
	public final IDiff diff;
	/**
	 * The direction in which data is copied, either EVENT_COPY_TO_TARGET
	 * or EVENT_COPY_TO_MODEL.
	 */
	public final int copyType;
	/**
	 * The position in the processing pipeline where this event is occuring. One
	 * of the PIPELINE_* constants. The order in which these events occur may be
	 * version or implementation dependent. The contract is that these events
	 * will accurately reflect the internal processing that the data binding
	 * framework is currently performing.
	 * <p>
	 * Although this value is not declared final, changing it does not have any
	 * effect.
	 */