Bug 126839 [DataBinding] IObservable refactoring
bundles/org.eclipse.jface.databinding/src/org/eclipse/jface/internal/provisional/databinding/IUpdatableCollection.java
/**
	 * @param value
	 * @param index
	 * @return the index where the element was added
	 */
	public int addElement(Object value, int index);
	/**
	 * @param index
	 */