show busy indicator in menu when triggered from shortcut

web-extension/background.js

@@ -433,5 +433,8 @@ footer, canvas {
     if (request.type === 'set include style') {
         chrome.storage.local.set({'includeStyle': request.includeStyle});
     }
+    if (request.type === 'is busy?') {
+        sendResponse({isBusy: isBusy})
+    }
     return true;
 });

web-extension/menu.js

@@ -13,6 +13,14 @@ document.getElementById('selectionChapterLabel').innerHTML = chrome.i18n.getMess
 document.getElementById('editChapters').innerHTML = chrome.i18n.getMessage('editChapters');
 document.getElementById('waitMessage').innerHTML = chrome.i18n.getMessage('waitMessage');
 
+checkIfBusy((result) => {
+    if (result.isBusy) {
+        document.getElementById('busy').style.display = 'block';
+    } else {
+        document.getElementById('busy').style.display = 'none';
+    }
+})
+
 getStyles(createStyleList);
 
 function createStyleList(styles) {

web-extension/utils.js

@@ -83,6 +83,14 @@ function removeEbook() {
     }, function(response) {});
 }
 
+function checkIfBusy(callback) {
+    chrome.runtime.sendMessage({
+        type: "is busy?"
+    }, function(response) {
+        callback(response);
+    });
+}
+
 /////
 function getCurrentUrl() {
     var url = window.location.href;