diff --git a/browser/base/content/popup-notifications.inc b/browser/base/content/popup-notifications.inc
index a6a219cdc2ff..d1ed57ce1d21 100644
--- a/browser/base/content/popup-notifications.inc
+++ b/browser/base/content/popup-notifications.inc
@@ -18,6 +18,17 @@
           <menupopup id="webRTC-selectCamera-menupopup"/>
         </menulist>
       </popupnotificationcontent>
+
+      <popupnotificationcontent id="webRTC-selectWindowOrScreen" orient="vertical">
+        <separator class="thin"/>
+        <label value="&getUserMedia.selectWindowOrScreen.label;"
+               accesskey="&getUserMedia.selectWindowOrScreen.accesskey;"
+               control="webRTC-selectWindow-menulist"/>
+        <menulist id="webRTC-selectWindow-menulist">
+          <menupopup id="webRTC-selectWindow-menupopup"/>
+        </menulist>
+      </popupnotificationcontent>
+
       <popupnotificationcontent id="webRTC-selectMicrophone" orient="vertical">
         <separator class="thin"/>
         <label value="&getUserMedia.selectMicrophone.label;"
diff --git a/browser/locales/en-US/chrome/browser/browser.dtd b/browser/locales/en-US/chrome/browser/browser.dtd
index da3957e3f8e1..677cb16d8da6 100644
--- a/browser/locales/en-US/chrome/browser/browser.dtd
+++ b/browser/locales/en-US/chrome/browser/browser.dtd
@@ -709,6 +709,8 @@ just addresses the organization to follow, e.g. "This site is run by " -->
 
 <!ENTITY getUserMedia.selectCamera.label "Camera to share:">
 <!ENTITY getUserMedia.selectCamera.accesskey "C">
+<!ENTITY getUserMedia.selectWindowOrScreen.label "Window or screen to share:">
+<!ENTITY getUserMedia.selectWindowOrScreen.accesskey "W">
 <!ENTITY getUserMedia.selectMicrophone.label "Microphone to share:">
 <!ENTITY getUserMedia.selectMicrophone.accesskey "M">
 
diff --git a/browser/locales/en-US/chrome/browser/browser.properties b/browser/locales/en-US/chrome/browser/browser.properties
index a838c0c9137e..ddd78c2aea5e 100644
--- a/browser/locales/en-US/chrome/browser/browser.properties
+++ b/browser/locales/en-US/chrome/browser/browser.properties
@@ -484,16 +484,23 @@ identity.loggedIn.description = Signed in as: %S
 identity.loggedIn.signOut.label = Sign Out
 identity.loggedIn.signOut.accessKey = O
 
-# LOCALIZATION NOTE (getUserMedia.shareCamera.message, getUserMedia.shareMicrophone.message, getUserMedia.shareCameraAndMicrophone.message): %S is the website origin (e.g. www.mozilla.org)
+# LOCALIZATION NOTE (getUserMedia.shareCamera.message, getUserMedia.shareMicrophone.message,
+#                    getUserMedia.shareScreen.message, getUserMedia.shareCameraAndMicrophone.message,
+#                    getUserMedia.shareScreenAndMicrophone.message):
+#  %S is the website origin (e.g. www.mozilla.org)
+getUserMedia.shareCamera.message = Would you like to share your camera with %S?
+getUserMedia.shareMicrophone.message = Would you like to share your microphone with %S?
+getUserMedia.shareScreen.message = Would you like to share your screen with %S?
+getUserMedia.shareCameraAndMicrophone.message = Would you like to share your camera and microphone with %S?
+getUserMedia.shareScreenAndMicrophone.message = Would you like to share your microphone and screen with %S?
+getUserMedia.noVideo.label = No Video
+getUserMedia.noWindowOrScreen.label = No Window or Screen
+getUserMedia.noAudio.label = No Audio
+getUserMedia.shareEntireScreen.label = Entire screen
 # LOCALIZATION NOTE (getUserMedia.shareSelectedDevices.label):
 # Semicolon-separated list of plural forms. See:
 # http://developer.mozilla.org/en/docs/Localization_and_Plurals
 # The number of devices can be either one or two.
-getUserMedia.shareCamera.message = Would you like to share your camera with %S?
-getUserMedia.shareMicrophone.message = Would you like to share your microphone with %S?
-getUserMedia.shareCameraAndMicrophone.message = Would you like to share your camera and microphone with %S?
-getUserMedia.noVideo.label = No Video
-getUserMedia.noAudio.label = No Audio
 getUserMedia.shareSelectedDevices.label = Share Selected Device;Share Selected Devices
 getUserMedia.shareSelectedDevices.accesskey = S
 getUserMedia.always.label = Always Share
diff --git a/browser/modules/webrtcUI.jsm b/browser/modules/webrtcUI.jsm
index 8ebe773f4aa3..24256a994500 100644
--- a/browser/modules/webrtcUI.jsm
+++ b/browser/modules/webrtcUI.jsm
@@ -94,31 +94,36 @@ function denyRequest(aCallID, aError) {
   Services.obs.notifyObservers(msg, "getUserMedia:response:deny", aCallID);
 }
 
-function prompt(aContentWindow, aCallID, aAudioRequested, aVideoRequested, aDevices, aSecure) {
+function prompt(aContentWindow, aCallID, aAudio, aVideo, aDevices, aSecure) {
   let audioDevices = [];
   let videoDevices = [];
+
+  // MediaStreamConstraints defines video as 'boolean or MediaTrackConstraints'.
+  let sharingScreen = aVideo && typeof(aVideo) != "boolean" &&
+                      aVideo.mediaSource != "camera";
   for (let device of aDevices) {
     device = device.QueryInterface(Ci.nsIMediaDevice);
     switch (device.type) {
       case "audio":
-        if (aAudioRequested)
+        if (aAudio)
           audioDevices.push(device);
         break;
       case "video":
-        if (aVideoRequested)
+        // Verify that if we got a camera, we haven't requested a screen share,
+        // or that if we requested a screen share we aren't getting a camera.
+        if (aVideo && (device.mediaSource == "camera") != sharingScreen)
           videoDevices.push(device);
         break;
     }
   }
 
-  let requestType;
-  if (audioDevices.length && videoDevices.length)
-    requestType = "CameraAndMicrophone";
-  else if (audioDevices.length)
-    requestType = "Microphone";
-  else if (videoDevices.length)
-    requestType = "Camera";
-  else {
+  let requestTypes = [];
+  if (videoDevices.length)
+    requestTypes.push(sharingScreen ? "Screen" : "Camera");
+  if (audioDevices.length)
+    requestTypes.push("Microphone");
+
+  if (!requestTypes.length) {
     denyRequest(aCallID, "NO_DEVICES_FOUND");
     return;
   }
@@ -128,11 +133,11 @@ function prompt(aContentWindow, aCallID, aAudioRequested, aVideoRequested, aDevi
   let chromeDoc = browser.ownerDocument;
   let chromeWin = chromeDoc.defaultView;
   let stringBundle = chromeWin.gNavigatorBundle;
-  let message = stringBundle.getFormattedString("getUserMedia.share" + requestType + ".message",
-                                                [ uri.host ]);
+  let stringId = "getUserMedia.share" + requestTypes.join("And") + ".message";
+  let message = stringBundle.getFormattedString(stringId, [uri.host]);
 
   let mainAction = {
-    label: PluralForm.get(requestType == "CameraAndMicrophone" ? 2 : 1,
+    label: PluralForm.get(requestTypes.length,
                           stringBundle.getString("getUserMedia.shareSelectedDevices.label")),
     accessKey: stringBundle.getString("getUserMedia.shareSelectedDevices.accesskey"),
     // The real callback will be set during the "showing" event. The
@@ -148,8 +153,11 @@ function prompt(aContentWindow, aCallID, aAudioRequested, aVideoRequested, aDevi
       callback: function () {
         denyRequest(aCallID);
       }
-    },
-    {
+    }
+  ];
+
+  if (!sharingScreen) { // Bug 1037438: implement 'never' for screen sharing.
+    secondaryActions.push({
       label: stringBundle.getString("getUserMedia.never.label"),
       accessKey: stringBundle.getString("getUserMedia.never.accesskey"),
       callback: function () {
@@ -162,11 +170,13 @@ function prompt(aContentWindow, aCallID, aAudioRequested, aVideoRequested, aDevi
         if (videoDevices.length)
           perms.add(uri, "camera", perms.DENY_ACTION);
       }
-    }
-  ];
+    });
+  }
 
-  if (aSecure) {
-    // Don't show the 'Always' action if the connection isn't secure.
+  if (aSecure && !sharingScreen) {
+    // Don't show the 'Always' action if the connection isn't secure, or for
+    // screen sharing (because we can't guess which window the user wants to
+    // share without prompting).
     secondaryActions.unshift({
       label: stringBundle.getString("getUserMedia.always.label"),
       accessKey: stringBundle.getString("getUserMedia.always.accesskey"),
@@ -185,7 +195,9 @@ function prompt(aContentWindow, aCallID, aAudioRequested, aVideoRequested, aDevi
 
       if (aTopic == "shown") {
         let PopupNotifications = chromeDoc.defaultView.PopupNotifications;
-        let popupId = requestType == "Microphone" ? "Microphone" : "Devices";
+        let popupId = "Devices";
+        if (requestTypes.length == 1 && requestTypes[0] == "Microphone")
+          popupId = "Microphone";
         PopupNotifications.panel.firstChild.setAttribute("popupid", "webRTC-share" + popupId);
       }
 
@@ -206,6 +218,10 @@ function prompt(aContentWindow, aCallID, aAudioRequested, aVideoRequested, aDevi
         if (camPerm == perms.PROMPT_ACTION)
           camPerm = perms.UNKNOWN_ACTION;
 
+        // Screen sharing shouldn't follow the camera permissions.
+        if (videoDevices.length && sharingScreen)
+          camPerm = perms.UNKNOWN_ACTION;
+
         // We don't check that permissions are set to ALLOW_ACTION in this
         // test; only that they are set. This is because if audio is allowed
         // and video is denied persistently, we don't want to show the prompt,
@@ -235,6 +251,40 @@ function prompt(aContentWindow, aCallID, aAudioRequested, aVideoRequested, aDevi
         }
       }
 
+      function listScreenShareDevices(menupopup, devices) {
+        while (menupopup.lastChild)
+          menupopup.removeChild(menupopup.lastChild);
+
+        // "No Window or Screen" is the default because we can't pick a
+        // 'default' window to share.
+        addDeviceToList(menupopup,
+                        stringBundle.getString("getUserMedia.noWindowOrScreen.label"),
+                        "-1");
+
+        // Then add the 'Entire screen' item if mozGetUserMediaDevices returned it.
+        for (let i = 0; i < devices.length; ++i) {
+          if (devices[i].mediaSource == "screen") {
+            menupopup.appendChild(chromeDoc.createElement("menuseparator"));
+            addDeviceToList(menupopup,
+                            stringBundle.getString("getUserMedia.shareEntireScreen.label"),
+                            i);
+            break;
+          }
+        }
+
+        // Finally add all the window names.
+        let separatorNeeded = true;
+        for (let i = 0; i < devices.length; ++i) {
+          if (devices[i].mediaSource == "window") {
+            if (separatorNeeded) {
+              menupopup.appendChild(chromeDoc.createElement("menuseparator"));
+              separatorNeeded = false;
+            }
+            addDeviceToList(menupopup, devices[i].name, i);
+          }
+        }
+      }
+
       function addDeviceToList(menupopup, deviceName, deviceIndex) {
         let menuitem = chromeDoc.createElement("menuitem");
         menuitem.setAttribute("value", deviceIndex);
@@ -243,16 +293,22 @@ function prompt(aContentWindow, aCallID, aAudioRequested, aVideoRequested, aDevi
         menupopup.appendChild(menuitem);
       }
 
-      chromeDoc.getElementById("webRTC-selectCamera").hidden = !videoDevices.length;
+      chromeDoc.getElementById("webRTC-selectCamera").hidden = !videoDevices.length || sharingScreen;
+      chromeDoc.getElementById("webRTC-selectWindowOrScreen").hidden = !sharingScreen || !videoDevices.length;
       chromeDoc.getElementById("webRTC-selectMicrophone").hidden = !audioDevices.length;
 
       let camMenupopup = chromeDoc.getElementById("webRTC-selectCamera-menupopup");
+      let windowMenupopup = chromeDoc.getElementById("webRTC-selectWindow-menupopup");
       let micMenupopup = chromeDoc.getElementById("webRTC-selectMicrophone-menupopup");
-      listDevices(camMenupopup, videoDevices);
+      if (sharingScreen)
+        listScreenShareDevices(windowMenupopup, videoDevices);
+      else
+        listDevices(camMenupopup, videoDevices);
       listDevices(micMenupopup, audioDevices);
-      if (requestType == "CameraAndMicrophone") {
+      if (requestTypes.length == 2) {
         let stringBundle = chromeDoc.defaultView.gNavigatorBundle;
-        addDeviceToList(camMenupopup, stringBundle.getString("getUserMedia.noVideo.label"), "-1");
+        if (!sharingScreen)
+          addDeviceToList(camMenupopup, stringBundle.getString("getUserMedia.noVideo.label"), "-1");
         addDeviceToList(micMenupopup, stringBundle.getString("getUserMedia.noAudio.label"), "-1");
       }
 
@@ -261,7 +317,8 @@ function prompt(aContentWindow, aCallID, aAudioRequested, aVideoRequested, aDevi
                                .createInstance(Ci.nsISupportsArray);
         let perms = Services.perms;
         if (videoDevices.length) {
-          let videoDeviceIndex = chromeDoc.getElementById("webRTC-selectCamera-menulist").value;
+          let listId = "webRTC-select" + (sharingScreen ? "Window" : "Camera") + "-menulist";
+          let videoDeviceIndex = chromeDoc.getElementById(listId).value;
           let allowCamera = videoDeviceIndex != "-1";
           if (allowCamera)
             allowedDevices.AppendElement(videoDevices[videoDeviceIndex]);
@@ -292,8 +349,9 @@ function prompt(aContentWindow, aCallID, aAudioRequested, aVideoRequested, aDevi
     }
   };
 
-  let anchorId = requestType == "Microphone" ? "webRTC-shareMicrophone-notification-icon"
-                                             : "webRTC-shareDevices-notification-icon";
+  let anchorId = "webRTC-shareDevices-notification-icon";
+  if (requestTypes.length == 1 && requestTypes[0] == "Microphone")
+    anchorId = "webRTC-shareMicrophone-notification-icon";
   chromeWin.PopupNotifications.show(browser, "webRTC-shareDevices", message,
                                     anchorId, mainAction, secondaryActions, options);
 }