Hi Frederic,

Icy has that kind of event so you can actually listen them and react to it:

Icy.getMainInterface().addActiveViewerListener(new ActiveViewerListener()
{
  @Override
  public void viewerDeactivated(Viewer viewer)
  {
    // call when viewer just has been de-activated / unfocused
  }

  @Override
  public void viewerActivated(Viewer viewer)
  {
    // call when viewer just has been activated / focused
  }

  @Override
  public void activeViewerChanged(ViewerEvent event)
  {
    // call when active/focused viewer has changed (Z/T position change for instance)
  }
});

Hope that was what you were looking for.

Best,

– Stephane