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.
bundles/org.eclipse.e4.ui.workbench/src/org/eclipse/e4/ui/internal/workbench/PartServiceImpl.java
} else {
				engine.createGui(part);
				MElementContainer<MUIElement> parent = part.getParent();
				if (parent.getChildren().size() == 1) {
					parent.setSelectedElement(part);
				}
			}
			return part;
		}
		return part;
	}
	public MPart showPart(String id, PartState partState) {
		Assert.isNotNull(id);
		Assert.isNotNull(partState);
		MPart part = findPart(id);
		if (part != null) {
			return showPart(part, partState);
		}
		MPartDescriptor descriptor = findDescriptor(id);
		part = createPart(descriptor);
		if (part == null) {
			return null;
		}
		return showPart(partState, part, part);
	}
	public MPart showPart(MPart part, PartState partState) {
		Assert.isNotNull(part);
		Assert.isNotNull(partState);
		MPart localPart = findPart(part.getElementId());
		if (localPart != null) {