app: adding browser-window-focus/blur events

atom/browser/api/lib/browser-window.coffee

@@ -30,6 +30,12 @@ BrowserWindow::_init = ->
   @on '-will-navigate', (event, url) =>
     @webContents.emit 'will-navigate', event, url
 
+  # Redirect focus/blur event to app instance too.
+  @on 'blur', (event) =>
+    app.emit 'browser-window-blur', event, this
+  @on 'focus', (event) =>
+    app.emit 'browser-window-focus', event, this
+
   # Remove the window from weak map immediately when it's destroyed, since we
   # could be iterating windows before GC happened.
   @once 'closed', =>
@@ -58,7 +64,7 @@ BrowserWindow.fromDevToolsWebContents = (webContents) ->
   return window for window in windows when window.devToolsWebContents?.equal webContents
 
 BrowserWindow.fromId = (id) ->
-  BrowserWindow.windows.get id
+  BrowserWindow.windows.get id if BrowserWindow.windows.has id
 
 # Helpers.
 BrowserWindow::loadUrl = -> @webContents.loadUrl.apply @webContents, arguments

docs/api/app.md

@@ -87,6 +87,20 @@ Emitted when the application is activated while there is no opened windows. It
 usually happens when user has closed all of application's windows and then
 click on the application's dock icon.
 
+## Event: browser-window-blur
+
+* `event` Event
+* `window` BrowserWindow
+
+Emitted when a [browserWindow](browser-window.md) gets blurred.
+
+## Event: browser-window-focus
+
+* `event` Event
+* `window` BrowserWindow
+
+Emitted when a [browserWindow](browser-window.md) gets focused.
+
 ## app.quit()
 
 Try to close all windows. The `before-quit` event will first be emitted. If all

spec/api-app-spec.coffee

@@ -1,5 +1,7 @@
 assert = require 'assert'
 app = require('remote').require 'app'
+remote = require 'remote'
+BrowserWindow = remote.require 'browser-window'
 
 describe 'app module', ->
   describe 'app.getVersion()', ->
@@ -23,3 +25,20 @@ describe 'app module', ->
       app.setName 'test-name'
       assert.equal app.getName(), 'test-name'
       app.setName 'Electron Test'
+
+  describe 'focus/blur event', ->
+    w = null
+    beforeEach ->
+      w.destroy() if w?
+      w = new BrowserWindow(show: false, width: 400, height: 400)
+    afterEach ->
+      w.destroy() if w?
+      w = null
+    it 'should emit focus event', (done) ->
+      app.once 'browser-window-blur', (e, window) ->
+        assert.equal w.id, window.id
+        done()
+      app.once 'browser-window-focus', (e, window) ->
+        assert.equal w.id, window.id
+        w.hide()
+      w.show()