Bug 324839 Secondary part selected by EPS due to initially selected part being hidden and removed does not get rendered
1. Have a stack with two parts in it, the selected one has been rendered, the other one is not. 2. Hide the selected part using the EPS. 3. The other part is now the selected part, but it is not rendered.
bundles/org.eclipse.e4.ui.workbench/src/org/eclipse/e4/ui/internal/workbench/PartServiceImpl.java
if (lastContainer != null) {
					return lastContainer;
				}
			}
		}
		return container;
	}
	/**
	 * Returns the parent container of the specified element. If one cannot be found, a check will
	 * be performed to see whether the element is being represented by a placeholder, if it is, the
	 * placeholder's parent will be returned, if any.
	 * 
	 * @param element
	 *            the element to query
	 * @return the element's parent container, or the parent container of the specified element's
	 *         current placeholder, if it has one
	 */
	private MElementContainer<MUIElement> getParent(MUIElement element) {
		MElementContainer<MUIElement> parent = element.getParent();
		if (parent == null) {
			MPlaceholder placeholder = element.getCurSharedRef();
			return placeholder == null ? null : placeholder.getParent();
		}
		return parent;
	}
	private MPart showPart(PartState partState, MPart providedPart, MPart localPart) {
		MPart part = addPart(providedPart, localPart);
		switch (partState) {
		case ACTIVATE:
			activate(part);