code: def text_changed(self):
          
          # Save text as bytes, if it was initially bytes
          if self.is_binary:
              self.text = to_binary_string(self.edit.toPlainText(), 'utf8')
          else:
              self.text = to_text_string(self.edit.toPlainText())
          if self.btn_save_and_close:
              self.btn_save_and_close.setEnabled(True)
              self.btn_save_and_close.setAutoDefault(True)
              self.btn_save_and_close.setDefault(True)
docs: Text has changed