Hide from Dock on macOS when the tray icon is enabled and the window is closed

app/dock_icon.js

@@ -0,0 +1,17 @@
+const { app } = require('electron');
+
+const dockIcon = {};
+
+dockIcon.show = () => {
+  if (process.platform === 'darwin') {
+    app.dock.show();
+  }
+};
+
+dockIcon.hide = () => {
+  if (process.platform === 'darwin') {
+    app.dock.hide();
+  }
+};
+
+module.exports = dockIcon;

app/tray_icon.js

@@ -2,6 +2,7 @@ const path = require('path');
 
 const fs = require('fs');
 const { app, Menu, Tray } = require('electron');
+const dockIcon = require('./dock_icon');
 
 let trayContextMenu = null;
 let tray = null;
@@ -34,8 +35,10 @@ function createTrayIcon(getMainWindow, messages) {
     if (mainWindow) {
       if (mainWindow.isVisible()) {
         mainWindow.hide();
+        dockIcon.hide();
       } else {
         mainWindow.show();
+        dockIcon.show();
 
         tray.forceOnTop(mainWindow);
       }

main.js

@@ -63,6 +63,7 @@ const attachments = require('./app/attachments');
 const attachmentChannel = require('./app/attachment_channel');
 const updater = require('./ts/updater/index');
 const createTrayIcon = require('./app/tray_icon');
+const dockIcon = require('./app/dock_icon');
 const ephemeralConfig = require('./app/ephemeral_config');
 const logging = require('./app/logging');
 const sql = require('./app/sql');
@@ -94,6 +95,9 @@ function showWindow() {
   if (tray) {
     tray.updateContextMenu();
   }
+
+  // show the app on the Dock in case it was hidden before
+  dockIcon.show();
 }
 
 if (!process.mas) {
@@ -366,6 +370,11 @@ function createWindow() {
         tray.updateContextMenu();
       }
 
+      // hide the app from the Dock on macOS if the tray icon is enabled
+      if (usingTrayIcon) {
+        dockIcon.hide();
+      }
+
       return;
     }