private DiagramGraphicalViewer viewer;
	protected final void displayDiagram(final Diagram diag) {

		if (diag == null) {
			return;
		}

		currentDiag = diag;
		
		// be sure the viewer will be correctly refreshed ( connections )
		viewer.getEditPartRegistry().clear();
		final DiagramRootEditPart rootEditPart = new DiagramRootEditPart(
				diag.getMeasurementUnit());
		viewer.setRootEditPart(rootEditPart);
		viewer.setContents(diag);

		enableEditMode((DiagramEditPart) viewer.getContents());
		rootEditPart.getZoomManager().setZoomAnimationStyle(
				ZoomManager.ANIMATE_NEVER);
		rootEditPart.getZoomManager().setZoom(ZOOM_FACTOR);
}