title: ROIListener usage
body: <p>I'm currently trying to make an ImageJ plugin that will make certain calculations based on two ROIs the user creates.</p>
  
  <p>Currently, I'm just trying to get <code>ROIListener</code> to work correctly. The roiModified() function is never called. Does anyone know what I'm doing wrong? The plugin loads and compiles fine.</p>
  
  <pre><code>public class Event_Listener implements PlugIn, RoiListener {
  
  public void run(String arg) {
      if (IJ.versionLessThan("1.43o")) return;
      Roi.addRoiListener(this);
      IJ.log("Event_Listener started");
  }
  
  @Override
  public void roiModified(ImagePlus imp, int id) {
      System.out.println(id);
      switch(id) {
      case RoiListener.CREATED:
          imp.getRoi().setFillColor(Color.black);
          System.out.println("ROI Created");
          break;
      }
  }
  </code></pre>