code: def _create_merge_button(self):
          
  
          bmp = icons["Merge"]
          self.mergetool_id = wx.NewId()
          self.AddCheckTool(self.mergetool_id, "Merge", bmp, bmp,
                            short_help_string=_("Merge cells"))
          self.Bind(wx.EVT_TOOL, self.OnMerge, id=self.mergetool_id)
docs: Create merge button