function onEdit(e) {
  try {
    var cell = e.range.getA1Notation();

    if (e.value && (cell === 'A6' || cell === 'E6')) {
      var sheet = e.source.getActiveSheet();
      var data = sheet.getRange('C4:G5').getValues();

      var langA = getLanguage(data[1][0]);
      var langB = getLanguage(data[1][4]);

      if (langA === '' || langB === '') {
        Browser.msgBox('Please select the languages of participants from the dropdowns in cell C5 and G5');
        return;
      }

      if (langA === langB) {
        Browser.msgBox('Please select a different language for each chat participant');
        return;
      }

      var userA = data[0][0];
      var userB = data[0][4];

      var colA, colB;

      if (cell === 'A6') {
        colA = userA + ': ' + e.value;
        colB = userA + ': ' + LanguageApp.translate(e.value, langA, langB);
      } else {
        colA = userB + ': ' + LanguageApp.translate(e.value, langB, langA);
        colB = userB + ': ' + e.value;
      }

      sheet.appendRow([colA, '', '', '', colB]);

      e.range.clearContent();
    }
  } catch (error) {
    Browser.msg(error.toString());
  }
}