Bug 322403 Showing a shared part with PartState.VISIBLE may not work correctly due to incorrect parent comparisons
We check the parents of the active part against the part-to-be-shown to determine how to respond when PartState.VISIBLE is used but the check is always 'true' for shared parts because getParent() returns 'null' for both parts. This is obviously wrong. We need to update the code to consider placeholders.
bundles/org.eclipse.e4.ui.workbench/src/org/eclipse/e4/ui/internal/workbench/PartServiceImpl.java
}
		return null;
	}
	private void internalFixContext(MPart part, MUIElement oldSelectedElement) {
		if (oldSelectedElement == null) {
			return;
		}
		MContext parentPart = getParentWithContext(oldSelectedElement);
		if (parentPart == null) {
			
			return;
		}
		IEclipseContext parentContext = parentPart.getContext();
		IEclipseContext oldContext = getSubContext(oldSelectedElement);
		Object child = parentContext.get(IContextConstants.ACTIVE_CHILD);
		if (child == null || oldContext == null || child == oldContext) {
			parentContext.set(IContextConstants.ACTIVE_CHILD,
					part == null ? null : part.getContext());
		}
	}
	public MPart findPart(String id) {
		MApplicationElement element = modelService.find(id, rootContainer);
		if (element instanceof MPlaceholder) {
			((MPlaceholder) element).getRef().setCurSharedRef((MPlaceholder) element);
			element = ((MPlaceholder) element).getRef();
		}
		return element instanceof MPart ? (MPart) element : null;
	}
	public Collection<MPart> getParts() {
		return modelService.findElements(rootContainer, null, MPart.class, null);