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
* @see org.eclipse.e4.ui.model.application.ui.basic.MPart#getToolbar()
	 * @see #getPart()
	 * @generated
	 */
	public EReference getPart_Toolbar() {
		return (EReference)partEClass.getEStructuralFeatures().get(1);
	}
	/**
	 * Returns the meta object for the attribute '{@link org.eclipse.e4.ui.model.application.ui.basic.MPart#isCloseable <em>Closeable</em>}'.
	 * <!-- begin-user-doc -->
	 * <!-- end-user-doc -->
	 * @return the meta object for the attribute '<em>Closeable</em>'.
	 * @see org.eclipse.e4.ui.model.application.ui.basic.MPart#isCloseable()
	 * @see #getPart()
	 * @generated
	 */
	public EAttribute getPart_Closeable() {
		return (EAttribute)partEClass.getEStructuralFeatures().get(2);
	}
	/**
	 * Returns the meta object for class '{@link org.eclipse.e4.ui.model.application.ui.basic.MInputPart <em>Input Part</em>}'.
	 * <!-- begin-user-doc -->
	 * <!-- end-user-doc -->
	 * @return the meta object for class '<em>Input Part</em>'.
	 * @see org.eclipse.e4.ui.model.application.ui.basic.MInputPart
	 * @generated
	 */
	public EClass getInputPart() {
		return inputPartEClass;
	}