Bug 339877 ToolBarManagerRenderer should not dispose of items that weren't created by the rendering engine
1. Window > Open Perspective > CVS Repository Exploring 2. The 'CVS Repositories' view doesn't have the 'Add CVS Repository' tool item. 3. Resizing the view doesn't help. 4. Close the view. 5. Reopen it. 6. Now it's there. Or maybe not, it didn't come back for Paul anyway.
bundles/org.eclipse.e4.ui.workbench.renderers.swt/src/org/eclipse/e4/ui/workbench/renderers/swt/ToolBarManagerRenderer.java
UIEvents.Item.SELECTED), selectionUpdater);
		eventBroker
				.subscribe(UIEvents.buildTopic(UIEvents.Item.TOPIC,
						UIEvents.Item.ENABLED), enabledUpdater);
		eventBroker.subscribe(UIEvents.buildTopic(UIEvents.UIElement.TOPIC),
				toBeRenderedUpdater);
		context.set(ToolBarManagerRenderer.class, this);
	}
	@PreDestroy
	public void contextDisposed() {
		eventBroker.unsubscribe(itemUpdater);
		eventBroker.unsubscribe(selectionUpdater);
		eventBroker.unsubscribe(enabledUpdater);
		eventBroker.unsubscribe(toBeRenderedUpdater);
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see
	 * org.eclipse.e4.ui.internal.workbench.swt.AbstractPartRenderer#createWidget
	 * (org.eclipse.e4.ui.model.application.ui.MUIElement, java.lang.Object)
	 */
	@Override
	public Object createWidget(final MUIElement element, Object parent) {
		if (!(element instanceof MToolBar) || !(parent instanceof Composite))
			return null;
		final MToolBar toolbarModel = (MToolBar) element;
		Composite intermediate = createIntermediate(toolbarModel,
				(Composite) parent);
		createToolbar(toolbarModel, intermediate);