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/BindSupportFactory.java
* Creates a validator for the given from and to types and model
	 * description. Either toType or modelDescription can be null, but not both.
	 * The returned validator (if not null) should validate arbitrary values of
	 * type toType, and (in the case that toType is given) ensure that they can
	 * be converted to toType, and (in the case that modelDescription is given)
	 * ensure that they can be converted to the type expected by updatable
	 * objects created from the given model description.
	 * 
	 * @param fromType
	 *            The type to validate
	 * @param toType
	 *            The type to convert to after successful validation, or
	 *            <code>null</code> if not known
	 * @return a validator, or <code>null</code> if this factory cannot create
	 *         a validator for the given arguments.
	 */
	public IValidator createValidator(Object fromType, Object toType) {
		return null;
	}
	/**
	 * Creates a domain validator for the given model description. Either
	 * modelType or modelDescription can be null, but not both.
	 * 
	 * @param modelType
	 *            The type to validate or <code>null</code> if not known
	 * @return IDomainValidator
	 */
	public IDomainValidator createDomainValidator(Object modelType) {
		return null;
	}