Bug 283340 NPE is thrown when last child of stack is removed
1. Close the 'Outline' view. 2. That stack is now gone. An NPE is logged. java.lang.NullPointerException at org.eclipse.e4.workbench.ui.renderers.swt.StackModelFactory.childRemoved(StackModelFactory.java:315) at org.eclipse.e4.workbench.ui.renderers.swt.StackModelFactory$2.notifyChanged(StackModelFactory.java:265) at org.eclipse.emf.common.notify.impl.BasicNotifierImpl.eNotify(BasicNotifierImpl.java:280) at org.eclipse.e4.ui.model.internal.application.MPartImpl.setVisible(MPartImpl.java:457) at org.eclipse.e4.workbench.ui.renderers.swt.StackModelFactory$5.close(StackModelFactory.java:344) at org.eclipse.swt.custom.CTabFolder.onMouse(CTabFolder.java:2199) at org.eclipse.swt.custom.CTabFolder$1.handleEvent(CTabFolder.java:327)
bundles/org.eclipse.e4.ui.workbench.renderers.swt/src/org/eclipse/e4/workbench/ui/renderers/swt/SWTPartRenderer.java
* org.eclipse.e4.ui.model.application.MPart)
	 */
	@Override
	public void childAdded(MPart<?> parentElement, MPart<?> element) {
		if (parentElement != null && element != null)
			return;
		
		
		if (element.getWidget() instanceof Control
				&& parentElement.getWidget() instanceof Composite) {
			Composite parentComp = (Composite) parentElement.getWidget();
			Control ctrl = (Control) element.getWidget();
			locallyShow(parentComp, ctrl);
		} else if (element.isVisible()) {
			
			renderer.createGui(element);
		}
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see
	 * org.eclipse.e4.workbench.ui.renderers.PartFactory#childRemoved(org.eclipse
	 * .e4.ui.model.application.MPart,
	 * org.eclipse.e4.ui.model.application.MPart)
	 */
	@Override
	public void childRemoved(MPart<?> parentElement, MPart<?> child) {
		super.childRemoved(parentElement, child);
		if (child.getWidget() instanceof Control) {