code: void dispose()
    {
      if( _pp == null )
      {
        return;
      }
  
      EditorUtilities.invokeInDispatchThread( () -> {
        if( _bShowInStudioGlassPane )
        {
          LabGlassPane.getInstance().removeModalComponent( _pp );
        }
        else
        {
          _pw.dispose();
        }
        _pp = null;
        _pw = null;
      } );
    }
docs: Hides and disposes the <code>ProgressWindow</code>.