diff --git a/app/ext-modules.d.ts b/app/ext-modules.d.ts
new file mode 100644
index 00000000..cbe6f667
--- /dev/null
+++ b/app/ext-modules.d.ts
@@ -0,0 +1,3 @@
+declare module 'git-describe' {
+  export function gitDescribe(...args: any[]): void;
+}
diff --git a/app/index.d.ts b/app/index.d.ts
new file mode 100644
index 00000000..1349d7d9
--- /dev/null
+++ b/app/index.d.ts
@@ -0,0 +1 @@
+// Dummy file, required by tsc
diff --git a/app/index.ts b/app/index.ts
index 49474b4e..5fba4d7e 100644
--- a/app/index.ts
+++ b/app/index.ts
@@ -1,5 +1,6 @@
 // Print diagnostic information for a few arguments instead of running Hyper.
 if (['--help', '-v', '--version'].includes(process.argv[1])) {
+  // eslint-disable-next-line @typescript-eslint/no-var-requires
   const {version} = require('./package');
   const configLocation = process.platform === 'win32' ? `${process.env.userprofile}\\.hyper.js` : '~/.hyper.js';
   //eslint-disable-next-line no-console
@@ -25,6 +26,7 @@ const checkSquirrel = () => {
 
 // handle startup squirrel events
 if (process.platform === 'win32') {
+  // eslint-disable-next-line @typescript-eslint/no-var-requires
   const systemContextMenu = require('./system-context-menu');
 
   switch (process.argv[1]) {
@@ -53,16 +55,38 @@ import {gitDescribe} from 'git-describe';
 import isDev from 'electron-is-dev';
 import * as config from './config';
 
+// Hack - this declararion doesn't work when put into ./ext-modules.d.ts for some reason so it's in this file for the time being
+declare module 'electron' {
+  interface App {
+    config: typeof import('./config');
+    plugins: typeof import('./plugins');
+    getWindows: () => Set<BrowserWindow>;
+    getLastFocusedWindow: () => BrowserWindow | null;
+    windowCallback: (win: BrowserWindow) => void;
+    createWindow: (fn?: (win: BrowserWindow) => void, options?: Record<string, any>) => BrowserWindow;
+    setVersion: (version: string) => void;
+  }
+
+  type Server = import('./rpc').Server;
+  interface BrowserWindow {
+    uid: string;
+    sessions: Map<any, any>;
+    focusTime: number;
+    clean: () => void;
+    rpc: Server;
+  }
+}
+
 // set up config
 config.setup();
 
 import * as plugins from './plugins';
 import {installCLI} from './utils/cli-install';
 import * as AppMenu from './menus/menu';
-import Window from './ui/window';
+import {newWindow} from './ui/window';
 import * as windowUtils from './utils/window-utils';
 
-const windowSet = new Set([]);
+const windowSet = new Set<BrowserWindow>([]);
 
 // expose to plugins
 app.config = config;
@@ -89,7 +113,7 @@ if (isDev) {
   console.log('running in dev mode');
 
   // Override default appVersion which is set from package.json
-  gitDescribe({customArguments: ['--tags']}, (error, gitInfo) => {
+  gitDescribe({customArguments: ['--tags']}, (error: any, gitInfo: any) => {
     if (!error) {
       app.setVersion(gitInfo.raw);
     }
@@ -103,16 +127,30 @@ const url = `file://${resolve(isDev ? __dirname : app.getAppPath(), 'index.html'
 //eslint-disable-next-line no-console
 console.log('electron will open', url);
 
+function installDevExtensions(isDev_: boolean) {
+  if (!isDev_) {
+    return Promise.resolve([]);
+  }
+  // eslint-disable-next-line @typescript-eslint/no-var-requires
+  const installer = require('electron-devtools-installer') as typeof import('electron-devtools-installer');
+
+  const extensions = ['REACT_DEVELOPER_TOOLS', 'REDUX_DEVTOOLS'] as const;
+  const forceDownload = Boolean(process.env.UPGRADE_EXTENSIONS);
+
+  return Promise.all(extensions.map(name => installer.default(installer[name], forceDownload)));
+}
+
 app.on('ready', () =>
   installDevExtensions(isDev)
     .then(() => {
-      function createWindow(fn, options = {}) {
+      function createWindow(fn?: (win: BrowserWindow) => void, options: Record<string, any> = {}) {
         const cfg = plugins.getDecoratedConfig();
 
         const winSet = config.getWin();
         let [startX, startY] = winSet.position;
 
         const [width, height] = options.size ? options.size : cfg.windowSize || winSet.size;
+        // eslint-disable-next-line @typescript-eslint/no-var-requires
         const {screen} = require('electron');
 
         const winPos = options.position;
@@ -150,7 +188,7 @@ app.on('ready', () =>
           [startX, startY] = config.windowDefaults.windowPosition;
         }
 
-        const hwin = new Window({width, height, x: startX, y: startY}, cfg, fn);
+        const hwin = newWindow({width, height, x: startX, y: startY}, cfg, fn);
         windowSet.add(hwin);
         hwin.loadURL(url);
 
@@ -229,7 +267,7 @@ app.on('ready', () =>
 
 app.on('open-file', (event, path) => {
   const lastWindow = app.getLastFocusedWindow();
-  const callback = win => win.rpc.emit('open file', {path});
+  const callback = (win: BrowserWindow) => win.rpc.emit('open file', {path});
   if (lastWindow) {
     callback(lastWindow);
   } else if (!lastWindow && {}.hasOwnProperty.call(app, 'createWindow')) {
@@ -243,7 +281,7 @@ app.on('open-file', (event, path) => {
 
 app.on('open-url', (event, sshUrl) => {
   const lastWindow = app.getLastFocusedWindow();
-  const callback = win => win.rpc.emit('open ssh', sshUrl);
+  const callback = (win: BrowserWindow) => win.rpc.emit('open ssh', sshUrl);
   if (lastWindow) {
     callback(lastWindow);
   } else if (!lastWindow && {}.hasOwnProperty.call(app, 'createWindow')) {
@@ -254,15 +292,3 @@ app.on('open-url', (event, sshUrl) => {
     app.windowCallback = callback;
   }
 });
-
-function installDevExtensions(isDev_) {
-  if (!isDev_) {
-    return Promise.resolve();
-  }
-  const installer = require('electron-devtools-installer');
-
-  const extensions = ['REACT_DEVELOPER_TOOLS', 'REDUX_DEVTOOLS'];
-  const forceDownload = Boolean(process.env.UPGRADE_EXTENSIONS);
-
-  return Promise.all(extensions.map(name => installer.default(installer[name], forceDownload)));
-}
diff --git a/app/menus/menu.ts b/app/menus/menu.ts
index 5eb7b820..0a21d144 100644
--- a/app/menus/menu.ts
+++ b/app/menus/menu.ts
@@ -1,5 +1,5 @@
 // Packages
-import {app, dialog, Menu} from 'electron';
+import {app, dialog, Menu, BrowserWindow} from 'electron';
 
 // Utilities
 import {getConfig} from '../config';
@@ -18,13 +18,16 @@ import {getRendererTypes} from '../utils/renderer-utils';
 const appName = app.getName();
 const appVersion = app.getVersion();
 
-let menu_ = [];
+let menu_: Menu;
 
-export const createMenu = (createWindow, getLoadedPluginVersions) => {
+export const createMenu = (
+  createWindow: (fn?: (win: BrowserWindow) => void, options?: Record<string, any>) => BrowserWindow,
+  getLoadedPluginVersions: () => {name: string; version: string}[]
+) => {
   const config = getConfig();
   // We take only first shortcut in array for each command
   const allCommandKeys = getDecoratedKeymaps();
-  const commandKeys = Object.keys(allCommandKeys).reduce((result, command) => {
+  const commandKeys = Object.keys(allCommandKeys).reduce((result: Record<string, string>, command) => {
     result[command] = allCommandKeys[command][0];
     return result;
   }, {});
@@ -40,7 +43,7 @@ export const createMenu = (createWindow, getLoadedPluginVersions) => {
     const pluginList =
       loadedPlugins.length === 0 ? 'none' : loadedPlugins.map(plugin => `\n  ${plugin.name} (${plugin.version})`);
 
-    const rendererCounts = Object.values(getRendererTypes()).reduce((acc, type) => {
+    const rendererCounts = Object.values(getRendererTypes()).reduce((acc: Record<string, number>, type) => {
       acc[type] = acc[type] ? acc[type] + 1 : 1;
       return acc;
     }, {});
@@ -53,7 +56,7 @@ export const createMenu = (createWindow, getLoadedPluginVersions) => {
       message: `${appName} ${appVersion} (${updateChannel})`,
       detail: `Renderers: ${renderers}\nPlugins: ${pluginList}\n\nCreated by Guillermo Rauch\nCopyright © 2019 ZEIT, Inc.`,
       buttons: [],
-      icon
+      icon: icon as any
     });
   };
   const menu = [
@@ -69,7 +72,7 @@ export const createMenu = (createWindow, getLoadedPluginVersions) => {
   return menu;
 };
 
-export const buildMenu = template => {
+export const buildMenu = (template: Electron.MenuItemConstructorOptions[]): Electron.Menu => {
   menu_ = Menu.buildFromTemplate(template);
   return menu_;
 };
diff --git a/app/rpc.ts b/app/rpc.ts
index e964d141..5f9f39b4 100644
--- a/app/rpc.ts
+++ b/app/rpc.ts
@@ -1,9 +1,12 @@
 import {EventEmitter} from 'events';
-import {ipcMain} from 'electron';
+import {ipcMain, BrowserWindow} from 'electron';
 import uuid from 'uuid';
 
-class Server extends EventEmitter {
-  constructor(win) {
+export class Server extends EventEmitter {
+  destroyed = false;
+  win: BrowserWindow;
+  id!: string;
+  constructor(win: BrowserWindow) {
     super();
     this.win = win;
     this.ipcListener = this.ipcListener.bind(this);
@@ -29,11 +32,11 @@ class Server extends EventEmitter {
     return this.win.webContents;
   }
 
-  ipcListener(event, {ev, data}) {
+  ipcListener(event: any, {ev, data}: {ev: string; data: any}) {
     super.emit(ev, data);
   }
 
-  emit(ch, data) {
+  emit(ch: string, data: any): any {
     // This check is needed because data-batching can cause extra data to be
     // emitted after the window has already closed
     if (!this.win.isDestroyed()) {
@@ -53,6 +56,6 @@ class Server extends EventEmitter {
   }
 }
 
-export default win => {
+export default (win: BrowserWindow) => {
   return new Server(win);
 };
diff --git a/app/ui/window.ts b/app/ui/window.ts
index 9f830f67..99d45011 100644
--- a/app/ui/window.ts
+++ b/app/ui/window.ts
@@ -1,4 +1,4 @@
-import {app, BrowserWindow, shell, Menu} from 'electron';
+import {app, BrowserWindow, shell, Menu, BrowserWindowConstructorOptions} from 'electron';
 import {isAbsolute} from 'path';
 import {parse as parseUrl} from 'url';
 import uuid from 'uuid';
@@ -16,301 +16,303 @@ import {execCommand} from '../commands';
 import {setRendererType, unsetRendererType} from '../utils/renderer-utils';
 import {decorateSessionOptions, decorateSessionClass} from '../plugins';
 
-export default class Window {
-  constructor(options_, cfg, fn) {
-    const classOpts = Object.assign({uid: uuid.v4()});
-    app.plugins.decorateWindowClass(classOpts);
-    this.uid = classOpts.uid;
+export function newWindow(
+  options_: BrowserWindowConstructorOptions,
+  cfg: any,
+  fn?: (win: BrowserWindow) => void
+): BrowserWindow {
+  const classOpts = Object.assign({uid: uuid.v4()});
+  app.plugins.decorateWindowClass(classOpts);
 
-    app.plugins.onWindowClass(this);
-
-    const winOpts = Object.assign(
-      {
-        minWidth: 370,
-        minHeight: 190,
-        backgroundColor: toElectronBackgroundColor(cfg.backgroundColor || '#000'),
-        titleBarStyle: 'hiddenInset',
-        title: 'Hyper.app',
-        // we want to go frameless on Windows and Linux
-        frame: process.platform === 'darwin',
-        transparent: process.platform === 'darwin',
-        icon,
-        show: process.env.HYPER_DEBUG || process.env.HYPERTERM_DEBUG || isDev,
-        acceptFirstMouse: true,
-        webPreferences: {
-          nodeIntegration: true,
-          navigateOnDragDrop: true
-        }
-      },
-      options_
-    );
-
-    const window = new BrowserWindow(app.plugins.getDecoratedBrowserOptions(winOpts));
-    window.uid = classOpts.uid;
-
-    const rpc = createRPC(window);
-    const sessions = new Map();
-
-    const updateBackgroundColor = () => {
-      const cfg_ = app.plugins.getDecoratedConfig();
-      window.setBackgroundColor(toElectronBackgroundColor(cfg_.backgroundColor || '#000'));
-    };
-
-    // set working directory
-    let workingDirectory = cfgDir;
-    if (process.argv[1] && isAbsolute(process.argv[1])) {
-      workingDirectory = process.argv[1];
-    } else if (cfg.workingDirectory && isAbsolute(cfg.workingDirectory)) {
-      workingDirectory = cfg.workingDirectory;
-    }
-
-    // config changes
-    const cfgUnsubscribe = app.config.subscribe(() => {
-      const cfg_ = app.plugins.getDecoratedConfig();
-
-      // notify renderer
-      window.webContents.send('config change');
-
-      // notify user that shell changes require new sessions
-      if (cfg_.shell !== cfg.shell || JSON.stringify(cfg_.shellArgs) !== JSON.stringify(cfg.shellArgs)) {
-        notify('Shell configuration changed!', 'Open a new tab or window to start using the new shell');
+  const winOpts = Object.assign(
+    {
+      minWidth: 370,
+      minHeight: 190,
+      backgroundColor: toElectronBackgroundColor(cfg.backgroundColor || '#000'),
+      titleBarStyle: 'hiddenInset',
+      title: 'Hyper.app',
+      // we want to go frameless on Windows and Linux
+      frame: process.platform === 'darwin',
+      transparent: process.platform === 'darwin',
+      icon,
+      show: process.env.HYPER_DEBUG || process.env.HYPERTERM_DEBUG || isDev,
+      acceptFirstMouse: true,
+      webPreferences: {
+        nodeIntegration: true,
+        navigateOnDragDrop: true
       }
+    },
+    options_
+  );
 
-      // update background color if necessary
-      updateBackgroundColor();
+  const window = new BrowserWindow(app.plugins.getDecoratedBrowserOptions(winOpts));
+  window.uid = classOpts.uid;
 
-      cfg = cfg_;
-    });
+  app.plugins.onWindowClass(window);
+  window.uid = classOpts.uid;
 
-    rpc.on('init', () => {
-      window.show();
-      updateBackgroundColor();
+  const rpc = createRPC(window);
+  const sessions = new Map();
 
-      // If no callback is passed to createWindow,
-      // a new session will be created by default.
-      if (!fn) {
-        fn = win => win.rpc.emit('termgroup add req', {});
-      }
+  const updateBackgroundColor = () => {
+    const cfg_ = app.plugins.getDecoratedConfig();
+    window.setBackgroundColor(toElectronBackgroundColor(cfg_.backgroundColor || '#000'));
+  };
 
-      // app.windowCallback is the createWindow callback
-      // that can be set before the 'ready' app event
-      // and createWindow definition. It's executed in place of
-      // the callback passed as parameter, and deleted right after.
-      (app.windowCallback || fn)(window);
-      delete app.windowCallback;
-      fetchNotifications(window);
-      // auto updates
-      if (!isDev) {
-        updater(window);
-      } else {
-        //eslint-disable-next-line no-console
-        console.log('ignoring auto updates during dev');
-      }
-    });
-
-    function createSession(extraOptions = {}) {
-      const uid = uuid.v4();
-
-      // remove the rows and cols, the wrong value of them will break layout when init create
-      const defaultOptions = Object.assign(
-        {
-          cwd: workingDirectory,
-          splitDirection: undefined,
-          shell: cfg.shell,
-          shellArgs: cfg.shellArgs && Array.from(cfg.shellArgs)
-        },
-        extraOptions,
-        {uid}
-      );
-      const options = decorateSessionOptions(defaultOptions);
-      const DecoratedSession = decorateSessionClass(Session);
-      const session = new DecoratedSession(options);
-      sessions.set(uid, session);
-      return {session, options};
-    }
-
-    rpc.on('new', extraOptions => {
-      const {session, options} = createSession(extraOptions);
-
-      sessions.set(options.uid, session);
-      rpc.emit('session add', {
-        rows: options.rows,
-        cols: options.cols,
-        uid: options.uid,
-        splitDirection: options.splitDirection,
-        shell: session.shell,
-        pid: session.pty ? session.pty.pid : null,
-        activeUid: options.activeUid
-      });
-
-      session.on('data', data => {
-        rpc.emit('session data', data);
-      });
-
-      session.on('exit', () => {
-        rpc.emit('session exit', {uid: options.uid});
-        unsetRendererType(options.uid);
-        sessions.delete(options.uid);
-      });
-    });
-
-    rpc.on('exit', ({uid}) => {
-      const session = sessions.get(uid);
-      if (session) {
-        session.exit();
-      }
-    });
-    rpc.on('unmaximize', () => {
-      window.unmaximize();
-    });
-    rpc.on('maximize', () => {
-      window.maximize();
-    });
-    rpc.on('minimize', () => {
-      window.minimize();
-    });
-    rpc.on('resize', ({uid, cols, rows}) => {
-      const session = sessions.get(uid);
-      if (session) {
-        session.resize({cols, rows});
-      }
-    });
-    rpc.on('data', ({uid, data, escaped}) => {
-      const session = sessions.get(uid);
-      if (session) {
-        if (escaped) {
-          const escapedData = session.shell.endsWith('cmd.exe')
-            ? `"${data}"` // This is how cmd.exe does it
-            : `'${data.replace(/'/g, `'\\''`)}'`; // Inside a single-quoted string nothing is interpreted
-
-          session.write(escapedData);
-        } else {
-          session.write(data);
-        }
-      }
-    });
-    rpc.on('info renderer', ({uid, type}) => {
-      // Used in the "About" dialog
-      setRendererType(uid, type);
-    });
-    rpc.on('open external', ({url}) => {
-      shell.openExternal(url);
-    });
-    rpc.on('open context menu', selection => {
-      const {createWindow} = app;
-      const {buildFromTemplate} = Menu;
-      buildFromTemplate(contextMenuTemplate(createWindow, selection)).popup(window);
-    });
-    rpc.on('open hamburger menu', ({x, y}) => {
-      Menu.getApplicationMenu().popup({x: Math.ceil(x), y: Math.ceil(y)});
-    });
-    // Same deal as above, grabbing the window titlebar when the window
-    // is maximized on Windows results in unmaximize, without hitting any
-    // app buttons
-    for (const ev of ['maximize', 'unmaximize', 'minimize', 'restore']) {
-      window.on(ev, () => rpc.emit('windowGeometry change'));
-    }
-    window.on('move', () => {
-      const position = window.getPosition();
-      rpc.emit('move', {bounds: {x: position[0], y: position[1]}});
-    });
-    rpc.on('close', () => {
-      window.close();
-    });
-    rpc.on('command', command => {
-      const focusedWindow = BrowserWindow.getFocusedWindow();
-      execCommand(command, focusedWindow);
-    });
-    // pass on the full screen events from the window to react
-    rpc.win.on('enter-full-screen', () => {
-      rpc.emit('enter full screen');
-    });
-    rpc.win.on('leave-full-screen', () => {
-      rpc.emit('leave full screen');
-    });
-    const deleteSessions = () => {
-      sessions.forEach((session, key) => {
-        session.removeAllListeners();
-        session.destroy();
-        sessions.delete(key);
-      });
-    };
-    // we reset the rpc channel only upon
-    // subsequent refreshes (ie: F5)
-    let i = 0;
-    window.webContents.on('did-navigate', () => {
-      if (i++) {
-        deleteSessions();
-      }
-    });
-
-    // If file is dropped onto the terminal window, navigate event is prevented
-    // and his path is added to active session.
-    window.webContents.on('will-navigate', (event, url) => {
-      const protocol = typeof url === 'string' && parseUrl(url).protocol;
-      if (protocol === 'file:') {
-        event.preventDefault();
-
-        const path = fileUriToPath(url);
-
-        rpc.emit('session data send', {data: path, escaped: true});
-      } else if (protocol === 'http:' || protocol === 'https:') {
-        event.preventDefault();
-        rpc.emit('session data send', {data: url});
-      }
-    });
-
-    // xterm makes link clickable
-    window.webContents.on('new-window', (event, url) => {
-      const protocol = typeof url === 'string' && parseUrl(url).protocol;
-      if (protocol === 'http:' || protocol === 'https:') {
-        event.preventDefault();
-        shell.openExternal(url);
-      }
-    });
-
-    // expose internals to extension authors
-    window.rpc = rpc;
-    window.sessions = sessions;
-
-    const load = () => {
-      app.plugins.onWindow(window);
-    };
-
-    // load plugins
-    load();
-
-    const pluginsUnsubscribe = app.plugins.subscribe(err => {
-      if (!err) {
-        load();
-        window.webContents.send('plugins change');
-        updateBackgroundColor();
-      }
-    });
-
-    // Keep track of focus time of every window, to figure out
-    // which one of the existing window is the last focused.
-    // Works nicely even if a window is closed and removed.
-    const updateFocusTime = () => {
-      window.focusTime = process.uptime();
-    };
-
-    window.on('focus', () => {
-      updateFocusTime();
-    });
-
-    // the window can be closed by the browser process itself
-    window.clean = () => {
-      app.config.winRecord(window);
-      rpc.destroy();
-      deleteSessions();
-      cfgUnsubscribe();
-      pluginsUnsubscribe();
-    };
-    // Ensure focusTime is set on window open. The focus event doesn't
-    // fire from the dock (see bug #583)
-    updateFocusTime();
-
-    return window;
+  // set working directory
+  let workingDirectory = cfgDir;
+  if (process.argv[1] && isAbsolute(process.argv[1])) {
+    workingDirectory = process.argv[1];
+  } else if (cfg.workingDirectory && isAbsolute(cfg.workingDirectory)) {
+    workingDirectory = cfg.workingDirectory;
   }
+
+  // config changes
+  const cfgUnsubscribe = app.config.subscribe(() => {
+    const cfg_ = app.plugins.getDecoratedConfig();
+
+    // notify renderer
+    window.webContents.send('config change');
+
+    // notify user that shell changes require new sessions
+    if (cfg_.shell !== cfg.shell || JSON.stringify(cfg_.shellArgs) !== JSON.stringify(cfg.shellArgs)) {
+      notify('Shell configuration changed!', 'Open a new tab or window to start using the new shell');
+    }
+
+    // update background color if necessary
+    updateBackgroundColor();
+
+    cfg = cfg_;
+  });
+
+  rpc.on('init', () => {
+    window.show();
+    updateBackgroundColor();
+
+    // If no callback is passed to createWindow,
+    // a new session will be created by default.
+    if (!fn) {
+      fn = (win: BrowserWindow) => win.rpc.emit('termgroup add req', {});
+    }
+
+    // app.windowCallback is the createWindow callback
+    // that can be set before the 'ready' app event
+    // and createWindow definition. It's executed in place of
+    // the callback passed as parameter, and deleted right after.
+    (app.windowCallback || fn)(window);
+    delete app.windowCallback;
+    fetchNotifications(window);
+    // auto updates
+    if (!isDev) {
+      updater(window);
+    } else {
+      //eslint-disable-next-line no-console
+      console.log('ignoring auto updates during dev');
+    }
+  });
+
+  function createSession(extraOptions = {}) {
+    const uid = uuid.v4();
+
+    // remove the rows and cols, the wrong value of them will break layout when init create
+    const defaultOptions = Object.assign(
+      {
+        cwd: workingDirectory,
+        splitDirection: undefined,
+        shell: cfg.shell,
+        shellArgs: cfg.shellArgs && Array.from(cfg.shellArgs)
+      },
+      extraOptions,
+      {uid}
+    );
+    const options = decorateSessionOptions(defaultOptions);
+    const DecoratedSession = decorateSessionClass(Session);
+    const session = new DecoratedSession(options);
+    sessions.set(uid, session);
+    return {session, options};
+  }
+
+  rpc.on('new', extraOptions => {
+    const {session, options} = createSession(extraOptions);
+
+    sessions.set(options.uid, session);
+    rpc.emit('session add', {
+      rows: options.rows,
+      cols: options.cols,
+      uid: options.uid,
+      splitDirection: options.splitDirection,
+      shell: session.shell,
+      pid: session.pty ? session.pty.pid : null,
+      activeUid: options.activeUid
+    });
+
+    session.on('data', (data: any) => {
+      rpc.emit('session data', data);
+    });
+
+    session.on('exit', () => {
+      rpc.emit('session exit', {uid: options.uid});
+      unsetRendererType(options.uid);
+      sessions.delete(options.uid);
+    });
+  });
+
+  rpc.on('exit', ({uid}) => {
+    const session = sessions.get(uid);
+    if (session) {
+      session.exit();
+    }
+  });
+  rpc.on('unmaximize', () => {
+    window.unmaximize();
+  });
+  rpc.on('maximize', () => {
+    window.maximize();
+  });
+  rpc.on('minimize', () => {
+    window.minimize();
+  });
+  rpc.on('resize', ({uid, cols, rows}) => {
+    const session = sessions.get(uid);
+    if (session) {
+      session.resize({cols, rows});
+    }
+  });
+  rpc.on('data', ({uid, data, escaped}) => {
+    const session = sessions.get(uid);
+    if (session) {
+      if (escaped) {
+        const escapedData = session.shell.endsWith('cmd.exe')
+          ? `"${data}"` // This is how cmd.exe does it
+          : `'${data.replace(/'/g, `'\\''`)}'`; // Inside a single-quoted string nothing is interpreted
+
+        session.write(escapedData);
+      } else {
+        session.write(data);
+      }
+    }
+  });
+  rpc.on('info renderer', ({uid, type}) => {
+    // Used in the "About" dialog
+    setRendererType(uid, type);
+  });
+  rpc.on('open external', ({url}) => {
+    shell.openExternal(url);
+  });
+  rpc.on('open context menu', selection => {
+    const {createWindow} = app;
+    const {buildFromTemplate} = Menu;
+    buildFromTemplate(contextMenuTemplate(createWindow, selection)).popup({window});
+  });
+  rpc.on('open hamburger menu', ({x, y}) => {
+    Menu.getApplicationMenu()!.popup({x: Math.ceil(x), y: Math.ceil(y)});
+  });
+  // Same deal as above, grabbing the window titlebar when the window
+  // is maximized on Windows results in unmaximize, without hitting any
+  // app buttons
+  for (const ev of ['maximize', 'unmaximize', 'minimize', 'restore'] as any) {
+    window.on(ev, () => rpc.emit('windowGeometry change', {}));
+  }
+  window.on('move', () => {
+    const position = window.getPosition();
+    rpc.emit('move', {bounds: {x: position[0], y: position[1]}});
+  });
+  rpc.on('close', () => {
+    window.close();
+  });
+  rpc.on('command', command => {
+    const focusedWindow = BrowserWindow.getFocusedWindow();
+    execCommand(command, focusedWindow!);
+  });
+  // pass on the full screen events from the window to react
+  rpc.win.on('enter-full-screen', () => {
+    rpc.emit('enter full screen', {});
+  });
+  rpc.win.on('leave-full-screen', () => {
+    rpc.emit('leave full screen', {});
+  });
+  const deleteSessions = () => {
+    sessions.forEach((session, key) => {
+      session.removeAllListeners();
+      session.destroy();
+      sessions.delete(key);
+    });
+  };
+  // we reset the rpc channel only upon
+  // subsequent refreshes (ie: F5)
+  let i = 0;
+  window.webContents.on('did-navigate', () => {
+    if (i++) {
+      deleteSessions();
+    }
+  });
+
+  // If file is dropped onto the terminal window, navigate event is prevented
+  // and his path is added to active session.
+  window.webContents.on('will-navigate', (event, url) => {
+    const protocol = typeof url === 'string' && parseUrl(url).protocol;
+    if (protocol === 'file:') {
+      event.preventDefault();
+
+      const path = fileUriToPath(url);
+
+      rpc.emit('session data send', {data: path, escaped: true});
+    } else if (protocol === 'http:' || protocol === 'https:') {
+      event.preventDefault();
+      rpc.emit('session data send', {data: url});
+    }
+  });
+
+  // xterm makes link clickable
+  window.webContents.on('new-window', (event, url) => {
+    const protocol = typeof url === 'string' && parseUrl(url).protocol;
+    if (protocol === 'http:' || protocol === 'https:') {
+      event.preventDefault();
+      shell.openExternal(url);
+    }
+  });
+
+  // expose internals to extension authors
+  window.rpc = rpc;
+  window.sessions = sessions;
+
+  const load = () => {
+    app.plugins.onWindow(window);
+  };
+
+  // load plugins
+  load();
+
+  const pluginsUnsubscribe = app.plugins.subscribe((err: any) => {
+    if (!err) {
+      load();
+      window.webContents.send('plugins change');
+      updateBackgroundColor();
+    }
+  });
+
+  // Keep track of focus time of every window, to figure out
+  // which one of the existing window is the last focused.
+  // Works nicely even if a window is closed and removed.
+  const updateFocusTime = () => {
+    window.focusTime = process.uptime();
+  };
+
+  window.on('focus', () => {
+    updateFocusTime();
+  });
+
+  // the window can be closed by the browser process itself
+  window.clean = () => {
+    app.config.winRecord(window);
+    rpc.destroy();
+    deleteSessions();
+    cfgUnsubscribe();
+    pluginsUnsubscribe();
+  };
+  // Ensure focusTime is set on window open. The focus event doesn't
+  // fire from the dock (see bug #583)
+  updateFocusTime();
+
+  return window;
 }
diff --git a/package.json b/package.json
index 44d57f67..75a935e8 100644
--- a/package.json
+++ b/package.json
@@ -297,6 +297,7 @@
     "@types/args": "3.0.0",
     "@types/color": "3.0.0",
     "@types/columnify": "^1.5.0",
+    "@types/electron-devtools-installer": "2.2.0",
     "@types/mousetrap": "^1.6.3",
     "@types/node": "^12.12.18",
     "@types/pify": "3.0.2",
diff --git a/webpack.config.js b/webpack.config.js
index b4de0bb2..d245d55e 100644
--- a/webpack.config.js
+++ b/webpack.config.js
@@ -13,7 +13,7 @@ module.exports = [
     resolve: {
       extensions: ['.js', '.jsx', '.ts', '.tsx', '.json']
     },
-    entry: './app/index.js',
+    entry: './app/index.ts',
     output: {
       path: path.join(__dirname, 'target'),
       filename: 'ignore_this.js'
diff --git a/yarn.lock b/yarn.lock
index db6b0b74..88ab3f96 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -620,6 +620,11 @@
   resolved "https://registry.yarnpkg.com/@types/debug/-/debug-4.1.5.tgz#b14efa8852b7768d898906613c23f688713e02cd"
   integrity sha512-Q1y515GcOdTHgagaVFhHnIFQ38ygs/kmxdNpvpou+raI9UO3YZcHDngBSYKQklcKlvA7iuQlmIKbzvmxcOE9CQ==
 
+"@types/electron-devtools-installer@2.2.0":
+  version "2.2.0"
+  resolved "https://registry.yarnpkg.com/@types/electron-devtools-installer/-/electron-devtools-installer-2.2.0.tgz#32ee4ebbe99b3daf9847a6d2097dc00b5de94f10"
+  integrity sha512-HJNxpaOXuykCK4rQ6FOMxAA0NLFYsf7FiPFGmab0iQmtVBHSAfxzy3MRFpLTTDDWbV0yD2YsHOQvdu8yCqtCfw==
+
 "@types/eslint-visitor-keys@^1.0.0":
   version "1.0.0"
   resolved "https://registry.yarnpkg.com/@types/eslint-visitor-keys/-/eslint-visitor-keys-1.0.0.tgz#1ee30d79544ca84d68d4b3cdb0af4f205663dd2d"