How to use

initializeViewportUpdate

method

in

org.eclipse.jface.text.TextViewer

@Override
public void addViewportListener(IViewportListener listener) {
  if (fViewportListeners == null) {
    fViewportListeners= new ArrayList<>();
    initializeViewportUpdate();
  }
  if (!fViewportListeners.contains(listener))
    fViewportListeners.add(listener);
}

@Override
public void addViewportListener(IViewportListener listener) {
  if (fViewportListeners == null) {
    fViewportListeners= new ArrayList<>();
    initializeViewportUpdate();
  }
  if (!fViewportListeners.contains(listener))
    fViewportListeners.add(listener);
}

fCursorListener.install();
initializeViewportUpdate();

fCursorListener.install();
initializeViewportUpdate();