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
private void modelProcessSwitch(ToolBarManager parentManager,
			MToolBarElement childME) {
		if (childME instanceof MHandledToolItem) {
			MHandledToolItem itemModel = (MHandledToolItem) childME;
			processHandledItem(parentManager, itemModel);
		} else if (childME instanceof MDirectToolItem) {
			MDirectToolItem itemModel = (MDirectToolItem) childME;
			processDirectItem(parentManager, itemModel);
		} else if (childME instanceof MToolBarSeparator) {
			MToolBarSeparator itemModel = (MToolBarSeparator) childME;
			processSeparator(parentManager, itemModel);
		} else if (childME instanceof MToolControl) {
			MToolControl itemModel = (MToolControl) childME;
			processToolControl(parentManager, itemModel);
		}
	}
	/**
	 * @param parentManager
	 * @param itemModel
	 */
	private void processSeparator(ToolBarManager parentManager,
			MToolBarSeparator itemModel) {
		AbstractGroupMarker marker = null;
		if (itemModel.isVisible()) {
			marker = new Separator();
			marker.setId(itemModel.getElementId());
		} else {
			if (itemModel.getElementId() != null) {
				marker = new GroupMarker(itemModel.getElementId());
			}