Bug 327964 EPartService's hidePart may fail when trying to hide a shared part that's in a shared container
The placeholder retrieval code in the EPartService implementation doesn't go far down deep enough and actually stops at the shared container level. This causes the placeholder of the shared part to not be found.
tests/org.eclipse.e4.ui.tests/src/org/eclipse/e4/ui/tests/application/EPartServiceTest.java
assertNotNull(shownPart);
		assertEquals(createdPart, shownPart);
	}
	public void testShowPart_Part_MultipleNonexistent_TrueACTIVATE() {
		testShowPart_Part_MultipleNonexistent(true, PartState.ACTIVATE);
	}
	public void testShowPart_Part_MultipleNonexistent_FalseACTIVATE() {
		testShowPart_Part_MultipleNonexistent(false, PartState.ACTIVATE);
	}
	public void testShowPart_Part_MultipleNonexistent_TrueVISIBLE() {
		testShowPart_Part_MultipleNonexistent(true, PartState.VISIBLE);
	}
	public void testShowPart_Part_MultipleNonexistent_FalseVISIBLE() {
		testShowPart_Part_MultipleNonexistent(false, PartState.VISIBLE);
	}
	public void testShowPart_Part_MultipleNonexistent_TrueCREATE() {
		testShowPart_Part_MultipleNonexistent(true, PartState.CREATE);
	}
	public void testShowPart_Part_MultipleNonexistent_FalseCREATE() {
		testShowPart_Part_MultipleNonexistent(false, PartState.CREATE);
	}
	public void testShowPart_Part_MultipleWithoutCategory() {
		MApplication application = ApplicationFactoryImpl.eINSTANCE
				.createApplication();
		MWindow window = BasicFactoryImpl.eINSTANCE.createWindow();
		application.getChildren().add(window);
		application.setSelectedElement(window);
		MPartDescriptor partDescriptor = org.eclipse.e4.ui.model.application.descriptor.basic.impl.BasicFactoryImpl.eINSTANCE
				.createPartDescriptor();
		partDescriptor.setAllowMultiple(true);