// disallows the removal of this edit part from its parent
installEditPolicy(EditPolicy.COMPONENT_ROLE, new RootComponentEditPolicy());
// handles constraint changes (e.g. moving and/or resizing) of model
// elements and creation of new model elements
installEditPolicy(EditPolicy.LAYOUT_ROLE, new DiagramXYLayoutEditPolicy(getCastedModel().getPresentation()));
installEditPolicy("Snap Feedback", new SapphireSnapFeedbackPolicy(getPresentation().getResourceCache())); //$NON-NLS-1$
}