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
List<MPart> dirtyPartsList = Collections.unmodifiableList(new ArrayList<MPart>(
					dirtyParts));
			Save[] decisions = saveHandler.promptToSave(dirtyPartsList);
			for (Save decision : decisions) {
				if (decision == Save.CANCEL) {
					return false;
				}
			}
			for (int i = 0; i < decisions.length; i++) {
				if (decisions[i] == Save.YES) {
					if (!savePart(dirtyPartsList.get(i), false)) {
						return false;
					}
				}
			}
			return true;
		}
		for (MPart dirtyPart : dirtyParts) {
			if (!savePart(dirtyPart, false)) {
				return false;
			}
		}
		return true;
	}
	private Collection<MInputPart> getInputParts() {
		return modelService.findElements(getContainer(), null, MInputPart.class, null);
	}
	public Collection<MInputPart> getInputParts(String inputUri) {
		Assert.isNotNull(inputUri, "Input uri must not be null"); 
		Collection<MInputPart> rv = new ArrayList<MInputPart>();