Bug 327044 EPartService's hidePart(*) should unset the part's parent element if the part is the selected element
It is not valid to have a selected element that's TBR flag is 'false'.
tests/org.eclipse.e4.ui.tests/src/org/eclipse/e4/ui/tests/application/EPartServiceTest.java
getEngine().createGui(windowA);
		getEngine().createGui(windowB);
		EPartService partServiceA = (EPartService) partFrontA.getContext().get(
				EPartService.class.getName());
		EPartService partServiceB = (EPartService) partFrontB.getContext().get(
				EPartService.class.getName());
		partServiceA.activate(partBackA);
		assertEquals(windowA, application.getSelectedElement());
		IEclipseContext a = application.getContext();
		IEclipseContext c = (IEclipseContext) a
				.getLocal(IContextConstants.ACTIVE_CHILD);
		while (c != null) {
			a = c;
			c = (IEclipseContext) a.getLocal(IContextConstants.ACTIVE_CHILD);
		}
		MPart aPart = (MPart) a.get(MPart.class.getName());
		assertEquals(partBackA, aPart);
		partServiceB.activate(partBackB);
		assertEquals(windowB, application.getSelectedElement());
		a = application.getContext();
		c = (IEclipseContext) a.getLocal(IContextConstants.ACTIVE_CHILD);
		while (c != null) {
			a = c;
			c = (IEclipseContext) a.getLocal(IContextConstants.ACTIVE_CHILD);
		}
		aPart = (MPart) a.get(MPart.class.getName());
		assertEquals(partBackB, aPart);
	}
	public void testActivate_partService_activePart() {
		MApplication application = createApplication(new String[] {