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/PartActivationHistory.java
private MPart getActivationCandidate(MPart part) {
		
		Collection<MPart> candidates = part.getContext().get(EPartService.class).getParts();
		return findActivationCandidate(candidates, part);
	}
	/**
	 * Finds and returns a part that is a valid candidate to be granted activation.
	 */
	private MPart findActivationCandidate(Collection<MPart> candidates, MPart currentlyActivePart) {
		candidates.remove(currentlyActivePart);
		MPlaceholder activePlaceholder = partService.getLocalPlaceholder(currentlyActivePart);
		for (MPart candidate : candidates) {
			
			if (isValid(candidate)) {
				MPlaceholder placeholder = partService.getLocalPlaceholder(candidate);
				MElementContainer<MUIElement> parent = placeholder == null ? candidate.getParent()
						: placeholder.getParent();
				
				
				if (parent instanceof MGenericStack) {
					MUIElement selection = parent.getSelectedElement();
					
					if (selection == activePlaceholder || selection == currentlyActivePart) {
						return candidate;
					}
					
					if (selection == candidate || selection == placeholder) {
						return candidate;
					}
				} else {