Bug 317417 [Model] StackElement should be abstract and interface
StackElement is only a marker for improved containment hierarchies. We should at least make it abstract but also as an interface like WindowElement, ...
bundles/org.eclipse.e4.ui.model.workbench/src/org/eclipse/e4/ui/model/application/ui/basic/impl/BasicPackageImpl.java
* @generated
	 * @ordered
	 */
	public static final int TRIMMED_WINDOW__VISIBLE_WHEN = WINDOW__VISIBLE_WHEN;
	/**
	 * The feature id for the '<em><b>Children</b></em>' containment reference list.
	 * <!-- begin-user-doc -->
	 * <!-- end-user-doc -->
	 * @generated
	 * @ordered
	 */
	public static final int TRIMMED_WINDOW__CHILDREN = WINDOW__CHILDREN;
	/**
	 * The feature id for the '<em><b>Selected Element</b></em>' reference.
	 * <!-- begin-user-doc -->
	 * <!-- end-user-doc -->
	 * @generated
	 * @ordered
	 */
	public static final int TRIMMED_WINDOW__SELECTED_ELEMENT = WINDOW__SELECTED_ELEMENT;
	/**
	 * The feature id for the '<em><b>Label</b></em>' attribute.
	 * <!-- begin-user-doc -->
	 * <!-- end-user-doc -->
	 * @generated
	 * @ordered
	 */
	public static final int TRIMMED_WINDOW__LABEL = WINDOW__LABEL;
	/**
	 * The feature id for the '<em><b>Icon URI</b></em>' attribute.