message: only allow one extension window to be open
diff: import browser from "webextension-polyfill";
  +let extensionWindow = undefined;
  let panelId = undefined;
  +function browserAction() {
  + if (extensionWindow) {
  + browser.windows.update(extensionWindow.id, {
  + focused: true
  + }).catch(openPage);
  + } else {
  + openPage();
  + }
  +}
  +
  function openPage() {
  const getContentWindowInfo = browser.windows.getLastFocused();
  const getSideexWindowInfo = openWindowFromStorageResolution();
  @@ -27,7 +38,7 @@ function openPage() {
  .then(function(windowInfo) {
  console.log("get the window info");
  let contentWindowInfo = windowInfo[0];
  - let sideexWindowInfo = windowInfo[1];
  + let sideexWindowInfo = extensionWindow = windowInfo[1];
  console.log("contentWindowInfo Id:" + contentWindowInfo.id);
  console.log("contentWindowInfo:", contentWindowInfo);
  console.log("sideexWindowInfo Id:" + sideexWindowInfo.id);
  @@ -97,7 +108,7 @@ function sideIsValid(number) {
  return number && number.constructor.name === "Number" && number > 50;
  }
  -browser.browserAction.onClicked.addListener(openPage);
  +browser.browserAction.onClicked.addListener(browserAction);
  function disconnectAllTabs(tabs) {
  for (let tab of tabs) {
  