Bug 124683 [DataBinding] support binding to a multi-selection
This is not yet implemented, but people are asking for it.
bundles/org.eclipse.jface.databinding/src/org/eclipse/jface/databinding/viewers/ViewersObservables.java
/**
	 * @param selectionProvider
	 * @return the observable value tracking the (single) selection of the given
	 *         selection provider
	 */
	public static IObservableValue observeSingleSelection(
			ISelectionProvider selectionProvider) {
		return new SelectionProviderSingleSelectionObservableValue(
				SWTObservables.getRealm(Display.getDefault()),
				selectionProvider);
	}
}