code: def is_valid(self):
          
          for lineedit in self.lineedits:
              if lineedit in self.validate_data and lineedit.isEnabled():
                  validator, invalid_msg = self.validate_data[lineedit]
                  text = to_text_string(lineedit.text())
                  if not validator(text):
                      QMessageBox.critical(self, self.get_name(),
                                       "%s:<br><b>%s</b>" % (invalid_msg, text),
                                       QMessageBox.Ok)
                      return False
          return True
docs: Return True if all widget contents are valid