Bug 326175 WBWRenderer arbitrarily modifies the window's parent's active context chain
The window's parent's context arbitrarily changes its active child to the window being rendered in createWidget(*).
tests/org.eclipse.e4.ui.tests/src/org/eclipse/e4/ui/tests/workbench/PartRenderingEngineTests.java
MPartSashContainer container = BasicFactoryImpl.eINSTANCE
				.createPartSashContainer();
		window.getChildren().add(container);
		MPart partA = BasicFactoryImpl.eINSTANCE.createPart();
		partA.setElementId("partA");
		partA.setContributionURI("platform:/plugin/org.eclipse.e4.ui.tests/org.eclipse.e4.ui.tests.workbench.SampleView");
		MPart partB = BasicFactoryImpl.eINSTANCE.createPart();
		partB.setElementId("partB");
		partB.setContributionURI("platform:/plugin/org.eclipse.e4.ui.tests/org.eclipse.e4.ui.tests.workbench.SampleView");
		MPart partC = BasicFactoryImpl.eINSTANCE.createPart();
		partC.setElementId("partC");
		partC.setContributionURI("platform:/plugin/org.eclipse.e4.ui.tests/org.eclipse.e4.ui.tests.workbench.SampleView");
		container.getChildren().add(partA);
		container.getChildren().add(partB);
		container.getChildren().add(partC);
		wb = new E4Workbench(application, appContext);
		wb.createAndRunUI(window);
		
		
		container.setSelectedElement(partA);
		partB.setToBeRendered(false);
		assertTrue(
				"Changing the TBR of a non-selected element should not change the value of the container's seletedElement",
				container.getSelectedElement() == partA);
		
		
		container.setSelectedElement(partA);
		partA.setToBeRendered(false);
		assertTrue(
				"Changing the TBR of the selected element should have set the field to null",