diff --git a/github-electron/github-electron-renderer-tests.ts b/github-electron/github-electron-renderer-tests.ts
index 6ec4d0b2f..d995f4933 100644
--- a/github-electron/github-electron-renderer-tests.ts
+++ b/github-electron/github-electron-renderer-tests.ts
@@ -100,6 +100,41 @@ crashReporter.start({
 	autoSubmit: true
 });
 
+// desktopCapturer
+// https://github.com/atom/electron/blob/master/docs/api/desktop-capturer.md
+
+var desktopCapturer = require('electron').desktopCapturer;
+
+desktopCapturer.getSources({types: ['window', 'screen']}, function(error, sources) {
+	if (error) throw error;
+	for (var i = 0; i < sources.length; ++i) {
+		if (sources[i].name == "Electron") {
+				(navigator as any).webkitGetUserMedia({
+				audio: false,
+				video: {
+					mandatory: {
+						chromeMediaSource: 'desktop',
+						chromeMediaSourceId: sources[i].id,
+						minWidth: 1280,
+						maxWidth: 1280,
+						minHeight: 720,
+						maxHeight: 720
+					}
+				}
+			}, gotStream, getUserMediaError);
+			return;
+		}
+	}
+});
+
+function gotStream(stream: any) {
+	(document.querySelector('video') as HTMLVideoElement).src = URL.createObjectURL(stream);
+}
+
+function getUserMediaError(error: Error) {
+	console.log('getUserMediaError', error);
+}
+
 // nativeImage
 // https://github.com/atom/electron/blob/master/docs/api/native-image.md
 
diff --git a/github-electron/github-electron.desktop-capturer.d.ts b/github-electron/github-electron.desktop-capturer.d.ts
index 900c4a4db..d938a1ed0 100644
--- a/github-electron/github-electron.desktop-capturer.d.ts
+++ b/github-electron/github-electron.desktop-capturer.d.ts
@@ -6,13 +6,29 @@
 /// <reference path="github-electron.native-image.d.ts" />
 
 declare namespace Electron {
-
+	/**
+	 * The desktopCapturer module can be used to get available sources
+	 * that can be used to be captured with getUserMedia.
+	 */
 	interface DesktopCapturer {
+		/**
+		 * Starts a request to get all desktop sources.
+		 *
+		 * Note: There is no guarantee that the size of source.thumbnail is always
+		 * the same as the thumnbailSize in options. It also depends on the scale of the screen or window.
+		 */
 		getSources(options: any, callback: (error: Error, sources: DesktopCapturerSource[]) => any): void;
 	}
 
 	interface DesktopCapturerOptions {
-		types?: string[];
+		/**
+		 * The types of desktop sources to be captured.
+		 */
+		types?: ('screen' | 'window')[];
+		/**
+		 * The suggested size that thumbnail should be scaled.
+		 * Default: {width: 150, height: 150}
+		 */
 		thumbnailSize?: {
 			width: number;
 			height: number;
@@ -20,8 +36,20 @@ declare namespace Electron {
 	}
 
 	interface DesktopCapturerSource {
+		/**
+		 * The id of the captured window or screen used in navigator.webkitGetUserMedia.
+		 * The format looks like window:XX or screen:XX where XX is a random generated number.
+		 */
 		id: string;
+		/**
+		 * The described name of the capturing screen or window.
+		 * If the source is a screen, the name will be Entire Screen or Screen <index>;
+		 * if it is a window, the name will be the window’s title.
+		 */
 		name: string;
+		/**
+		 * A thumbnail image.
+		 */
 		thumbnail: NativeImage;
 	}
 }