Bug 304074 View toolbars don't go away when the view is closed
1. Run the compatibility layer. 2. Close the 'Package Explorer' view. 3. Its toolbar is still there.
bundles/org.eclipse.e4.ui.workbench.renderers.swt/src/org/eclipse/e4/workbench/ui/renderers/swt/StackRenderer.java
if (!(((MUIElement) parentElement) instanceof MPartStack)
				|| !(element instanceof MPart))
			return;
		createTab(parentElement, element);
	}
	private CTabItem findItemForPart(MUIElement part) {
		MElementContainer<MUIElement> stack = part.getParent();
		CTabFolder ctf = (CTabFolder) stack.getWidget();
		if (ctf == null)
			return null;
		CTabItem[] items = ctf.getItems();
		for (int i = 0; i < items.length; i++) {
			if (items[i].getData(OWNING_ME) == part)
				return items[i];
		}
		return null;
	}
	@Override
	public void hideChild(MElementContainer<MUIElement> parentElement,
			MUIElement child) {
		super.hideChild(parentElement, child);
		if (!(((MUIElement) parentElement) instanceof MPartStack)
				|| !(child instanceof MPart))
			return;
		CTabFolder ctf = (CTabFolder) parentElement.getWidget();
		if (ctf == null)
			return;
		
		CTabItem[] items = ctf.getItems();
		for (int i = 0; i < items.length; i++) {