Bug 334559 EPartService's part searching path may not include parts outside of the active perspective
bundles/org.eclipse.e4.ui.workbench/src/org/eclipse/e4/ui/internal/workbench/PartServiceImpl.java
private MElementContainer<?> getLastContainer(MElementContainer<?> container, List<?> children) {
		if (children.isEmpty()) {
			return null;
		}
		for (int i = children.size() - 1; i > -1; i--) {
			Object muiElement = children.get(i);
			if (muiElement instanceof MElementContainer<?>) {
				MElementContainer<?> childContainer = (MElementContainer<?>) muiElement;
				MElementContainer<?> lastContainer = getLastContainer(childContainer,
						childContainer.getChildren());
				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) {