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
} else {
					IContributionItem ici = modelToContribution
							.remove(itemModel);
					if (ici != null && parent != null) {
						parent.remove(ici);
					}
					if (ici != null) {
						ici.dispose();
					}
				}
			} else if (UIEvents.UIElement.VISIBLE.equals(attName)) {
				IContributionItem ici = getContribution(itemModel);
				if (ici == null) {
					return;
				}
				ici.setVisible(itemModel.isVisible());
				ToolBarManager parent = (ToolBarManager) ((ContributionItem) ici)
						.getParent();
				if (parent != null) {
					parent.markDirty();
					ToolBar tb = parent.getControl();
					if (tb != null && !tb.isDisposed()) {
						tb.getShell().layout(new Control[] { tb }, SWT.DEFER);
					}
				}
			}
		}
	};
	private EventHandler selectionUpdater = new EventHandler() {
		public void handleEvent(Event event) {