Bug 318713 Duplicate toolbar items (navigate group)
SDK 4.0 - I20100701-1105. 1. start fresh workspace ==> navigate group appears twice which is quite confusing and wastes space.
bundles/org.eclipse.e4.ui.workbench/src/org/eclipse/e4/ui/internal/workbench/ContributionsAnalyzer.java
for (MToolBarElement item : toolBarContribution.getChildren()) {
			MToolBarElement copy = (MToolBarElement) EcoreUtil.copy((EObject) item);
			if (DEBUG) {
				trace("addToolBarContribution " + copy, toolBarModel.getWidget(), toolBarModel); 
			}
			toolBarModel.getChildren().add(idx++, copy);
			contributions.add(copy);
		}
		return true;
	}
	public static boolean processAddition(final MTrimBar trimBar, MTrimContribution contribution,
			List<MTrimElement> contributions) {
		int idx = getIndex(trimBar, contribution.getPositionInParent());
		if (idx == -1) {
			return false;
		}
		for (MTrimElement item : contribution.getChildren()) {
			MTrimElement copy = (MTrimElement) EcoreUtil.copy((EObject) item);
			if (DEBUG) {
				trace("addTrimContribution " + copy, trimBar.getWidget(), trimBar); 
			}
			trimBar.getChildren().add(idx++, copy);
			contributions.add(copy);
		}
		return true;
	}
	private static int getIndex(MElementContainer<?> menuModel, String positionInParent) {
		String id = null;
		String modifier = null;
		if (positionInParent != null && positionInParent.length() > 0) {