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/StackRenderer.java
boolean showCloseAlways = false;
			int styleModifier = 0;
			if (part.getPolicy() != null && part.getPolicy().length() > 0) {
				String policy = part.getPolicy();
				if (policy.indexOf("ViewStack") >= 0) { 
					styleModifier = SWT.CLOSE;
				}
				if (policy.indexOf("EditorStack") >= 0) { 
					styleModifier = SWT.CLOSE;
					showCloseAlways = true;
				}
			}
			Composite stylingWrapper = createWrapperForStyling(
					(Composite) parentWidget, part.getContext());
			
			
			
			final CTabFolder ctf = new ETabFolder(stylingWrapper, SWT.BORDER
					| styleModifier);
			configureForStyling(ctf);
			ctf.setUnselectedCloseVisible(showCloseAlways);
			bindWidget(part, ctf);
			ctf.setVisible(true);
			newWidget = ctf;
			final IEclipseContext folderContext = part.getContext();
			folderContext.set(IContextConstants.DEBUG_STRING, "TabFolder"); 
			final IEclipseContext toplevelContext = getToplevelContext(part);