Bug 328946 Part activation history may return incorrect candidate if no placeholders could be found in a perspective
1. Window > Open Perspective > Other... > CVS Repository Exploring 2. Hide the 'CVS Repositories' view. 3. The 'History' view should become active, it is not.
tests/org.eclipse.e4.ui.tests/src/org/eclipse/e4/ui/tests/application/EPartServiceTest.java
MPerspective perspectiveA = AdvancedFactoryImpl.eINSTANCE
				.createPerspective();
		perspectiveStack.getChildren().add(perspectiveA);
		perspectiveStack.setSelectedElement(perspectiveA);
		MPartStack partStackA = BasicFactoryImpl.eINSTANCE.createPartStack();
		perspectiveA.getChildren().add(partStackA);
		perspectiveA.setSelectedElement(partStackA);
		MPlaceholder partPlaceholderA1 = AdvancedFactoryImpl.eINSTANCE
				.createPlaceholder();
		partPlaceholderA1.setRef(partA);
		partA.setCurSharedRef(partPlaceholderA1);
		partStackA.getChildren().add(partPlaceholderA1);
		partStackA.setSelectedElement(partPlaceholderA1);
		MPlaceholder partPlaceholderB1 = AdvancedFactoryImpl.eINSTANCE
				.createPlaceholder();
		partPlaceholderB1.setRef(partB);
		partB.setCurSharedRef(partPlaceholderB1);
		partStackA.getChildren().add(partPlaceholderB1);
		MPerspective perspectiveB = AdvancedFactoryImpl.eINSTANCE
				.createPerspective();
		perspectiveStack.getChildren().add(perspectiveB);
		MPartStack partStackB = BasicFactoryImpl.eINSTANCE.createPartStack();
		perspectiveB.getChildren().add(partStackB);
		perspectiveB.setSelectedElement(partStackB);
		MPlaceholder partPlaceholderA2 = AdvancedFactoryImpl.eINSTANCE
				.createPlaceholder();
		partPlaceholderA2.setRef(partA);
		partStackB.getChildren().add(partPlaceholderA2);
		partStackB.setSelectedElement(partPlaceholderA2);
		MPlaceholder partPlaceholderB2 = AdvancedFactoryImpl.eINSTANCE