Bug 319319 Window menu lists too many top-level windows
see screenshot
bundles/org.eclipse.e4.ui.workbench.renderers.swt/src/org/eclipse/e4/ui/workbench/renderers/swt/RenderedMenuItemRenderer.java
public Object createWidget(final MUIElement element, Object parent) {
		if (!(element instanceof MRenderedMenuItem)
				|| !(parent instanceof Menu)) {
			return null;
		}
		MRenderedMenuItem menuModel = (MRenderedMenuItem) element;
		Object contribution = menuModel.getContributionItem();
		if (contribution instanceof ExtensionPointProxy) {
			ExtensionPointProxy proxy = (ExtensionPointProxy) contribution;
			Object delegate = proxy.createDelegate(menuModel);
			if (delegate != null) {