code: def pan_pan_cb(self, fitsimage, event):
          
          chviewer = self.fv.getfocus_viewer()
          bd = chviewer.get_bindings()
  
          if hasattr(bd, 'pa_pan'):
              return bd.pa_pan(chviewer, event)
  
          return False
docs: Pan event in the pan window.  Just pan the channel viewer.