public IDeleteFeature getDeleteFeature(IDeleteContext context) {
		PictogramElement pictogramElement = context.getPictogramElement();
		if (pictogramElement instanceof ContainerShape) {
			Object bo = getBusinessObjectForPictogramElement(pictogramElement);
			if ((bo instanceof Application) || (bo instanceof Operation) || (bo instanceof User))
				return new CantDeleteFeature(this);
		}
		if (pictogramElement instanceof Connection) {
			Connection connection = (Connection) pictogramElement;
			Object sourceElement = getBusinessObjectForPictogramElement(connection.getStart().getParent());
			Object targetElement = getBusinessObjectForPictogramElement(connection.getEnd().getParent());
			if ((sourceElement instanceof Application) && (targetElement instanceof Operation))
				return new InvokesDeleteFeature(this);
			if ((sourceElement instanceof User) && (targetElement instanceof Application))
				return new UsesDeleteFeature(this);
		}
		return super.getDeleteFeature(context);
	}

...
if (editParts.size() > 0) {
	final EditPart editpart = editParts.get(0);
	// if the editPart is newly created it is possible that his
	// figure has not a valid bounds. Hence we have to wait for
	// the UI update (for the validation of the figure tree).
	// Otherwise the reveal method can't work correctly.
	Display.getDefault().asyncExec(new Runnable() {
		public void run() {
			try {
				getDiagramContainer().getGraphicalViewer().reveal(editpart);
			} catch (NullPointerException e) {
				// Simply catch NPE as workaround for bug 428227
			}
		}
	});
}
...