Bug 329482 Uninstantiated part may be rendered when closing another part in the same stack
1. Activate the 'Javadoc' view. 2. Activate the 'Package Explorer' view. 3. Shutdown. 4. Restart. 5. Ctrl+3 > Properties 6. Hide the 'Properties' view. 7. Now the 'Problems' view is the selected element. It should be the 'Javadoc' view.
bundles/org.eclipse.e4.ui.workbench/src/org/eclipse/e4/ui/internal/workbench/PartServiceImpl.java
if (sharedPart == null) {
			MPartDescriptor descriptor = findDescriptor(id);
			sharedPart = createPart(descriptor);
			if (sharedPart == null) {
				return null;
			}
			sharedWindow.getSharedElements().add(sharedPart);
		}
		return createSharedPart(sharedPart);
	}
	private MPlaceholder createSharedPart(MPart sharedPart) {
		
		MPlaceholder sharedPartRef = AdvancedFactoryImpl.eINSTANCE.createPlaceholder();
		sharedPartRef.setElementId(sharedPart.getElementId());
		sharedPartRef.setRef(sharedPart);
		return sharedPartRef;
	}
	private MPart addPart(MPart providedPart, MPart localPart) {
		
		if (providedPart == localPart && isInContainer(providedPart)) {
			return providedPart;
		}
		MPartDescriptor descriptor = findDescriptor(providedPart.getElementId());
		if (descriptor == null) {
			if (!isInContainer(providedPart)) {
				adjustPlaceholder(providedPart);
				addToLastContainer(null, providedPart);
			}
		} else {
			if (providedPart != localPart && !descriptor.isAllowMultiple()) {