code: def unzoom(self, event=None, set_bounds=True):
          
          lims = None
          if len(self.conf.zoom_lims) > 1:
              lims = self.conf.zoom_lims.pop()
          ax = self.axes
          # print 'base unzoom ', lims, set_bounds
          if lims is None: # auto scale
              self.conf.zoom_lims = [None]
              xmin, xmax, ymin, ymax = self.data_range
              ax.set_xlim((xmin, xmax), emit=True)
              ax.set_ylim((ymin, ymax), emit=True)
              if set_bounds:
                  ax.update_datalim(((xmin, ymin), (xmax, ymax)))
                  ax.set_xbound(ax.xaxis.get_major_locator(
                      ).view_limits(xmin, xmax))
                  ax.set_ybound(ax.yaxis.get_major_locator(
                      ).view_limits(ymin, ymax))
          else:
              self.set_viewlimits()
  
          self.canvas.draw()
docs: zoom out 1 level, or to full data range