code: def on_update_page_links(self, evt):
          
          if not self.update_links:                 # skip if unsupported links
              evt.Skip()
              return
          pg = self.doc[getint(self.TextToPage.Value) -1]
          for i in range(len(self.page_links)):
              l = self.page_links[i]
              if l.get("update", False):            # "update" must be True
                  if l["xref"] == 0:                # no xref => new link
                      pg.insertLink(l)
                  elif l["kind"] < 1 or l["kind"] > len(self.linkTypeStrings):
                      pg.deleteLink(l)              # delete invalid link
                  else:
                      pg.updateLink(l)              # else link update
              l["update"] = False                   # reset update indicator
              self.page_links[i] = l                # update list of page links
          self.btn_Update.Disable()                 # disable update button
          self.t_Update.Label = ""                  # and its message
          self.btn_Save.Enable()
          self.t_Save.Label = "There are changes. Press to save them to file."
          evt.Skip()
          return
docs: Perform PDF update of changed links.