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
return false;
		} else if (parent instanceof MGenericStack && parent.getSelectedElement() != element) {
			
			return false;
		}
		return isValid(perspective, parent);
	}
	/**
	 * Determines whether this element is contained within an MArea, and to return the area if it
	 * is.
	 */
	private MArea isInArea(MUIElement element) {
		MPlaceholder placeholder = element.getCurSharedRef();
		if (placeholder == null) {
			MUIElement parent = element.getParent();
			if (parent == null) {
				
				parent = (MUIElement) ((EObject) element).eContainer();
			}
			return parent instanceof MApplication ? null : parent instanceof MArea ? (MArea) parent
					: isInArea(parent);
		}
		MUIElement parent = placeholder.getParent();
		if (parent == null) {
			
			parent = (MUIElement) ((EObject) placeholder).eContainer();
		}
		return parent instanceof MApplication ? null : parent instanceof MArea ? (MArea) parent
				: isInArea(parent);
	}