Display.getDefault().asyncExec(new Runnable(){
public void run() {
IMap activeMap = ApplicationGIS.getActiveMap();
ViewportModel viewportModel = (ViewportModel) activeMap.getViewportModel();
activeMap.addMapListener(NavigationView.this);
activeMap.addMapCompositionListener(NavigationView.this);
ReferencedEnvelope bounds = viewportModel.getBounds();
double west = bounds.getMinX();
double east = bounds.getMaxX();