--- a/mobile/xul/chrome/content/common-ui.js
+++ b/mobile/xul/chrome/content/common-ui.js
@@ -1171,17 +1171,18 @@ var FullScreenVideo = {
     messageManager.addMessageListener("Browser:FullScreenVideo:Close", this.hide.bind(this));
     messageManager.addMessageListener("Browser:FullScreenVideo:Play", this.play.bind(this));
     messageManager.addMessageListener("Browser:FullScreenVideo:Pause", this.pause.bind(this));
 
     // If the screen supports brightness locks, we will utilize that, see checkBrightnessLocking()
     try {
       this.screen = null;
       let screenManager = Cc["@mozilla.org/gfx/screenmanager;1"].getService(Ci.nsIScreenManager);
-      this.screen = screenManager.primaryScreen;
+      let screen = screenManager.primaryScreen.QueryInterface(Ci.nsIScreen_MOZILLA_2_0_BRANCH);
+      this.screen = screen;
     }
     catch (e) {} // The screen does not support brightness locks
   },
 
   play: function() {
     this.playing = true;
     this.checkBrightnessLocking();
   },

--- a/widget/android/nsScreenManagerAndroid.cpp
+++ b/widget/android/nsScreenManagerAndroid.cpp
@@ -37,16 +37,18 @@
  * ***** END LICENSE BLOCK ***** */
 
 #include "nsScreenManagerAndroid.h"
 #include "nsWindow.h"
 #include "AndroidBridge.h"
 
 using namespace mozilla;
 
+NS_IMPL_ISUPPORTS2(nsScreenAndroid, nsIScreen, nsIScreen_MOZILLA_2_0_BRANCH)
+
 nsScreenAndroid::nsScreenAndroid(void *nativeScreen)
 {
 }
 
 nsScreenAndroid::~nsScreenAndroid()
 {
 }
 

--- a/widget/android/nsScreenManagerAndroid.h
+++ b/widget/android/nsScreenManagerAndroid.h
@@ -36,33 +36,33 @@
  *
  * ***** END LICENSE BLOCK ***** */
 
 #ifndef nsScreenManagerAndroid_h___
 #define nsScreenManagerAndroid_h___
 
 #include "nsCOMPtr.h"
 
-#include "nsBaseScreen.h"
 #include "nsIScreenManager.h"
+#include "nsIScreen.h"
 #include "WidgetUtils.h"
 
-class nsScreenAndroid : public nsBaseScreen
+class nsScreenAndroid
+  : public nsIScreen
+  , public mozilla::widget::BrightnessLockingWidget
 {
 public:
     nsScreenAndroid(void *nativeScreen);
     ~nsScreenAndroid();
 
-    NS_IMETHOD GetRect(PRInt32* aLeft, PRInt32* aTop, PRInt32* aWidth, PRInt32* aHeight);
-    NS_IMETHOD GetAvailRect(PRInt32* aLeft, PRInt32* aTop, PRInt32* aWidth, PRInt32* aHeight);
-    NS_IMETHOD GetPixelDepth(PRInt32* aPixelDepth);
-    NS_IMETHOD GetColorDepth(PRInt32* aColorDepth);
+    NS_DECL_ISUPPORTS
+    NS_DECL_NSISCREEN
 
 protected:
-    virtual void ApplyMinimumBrightness(PRUint32 aBrightness) MOZ_OVERRIDE;
+    void ApplyMinimumBrightness(PRUint32 aBrightness);
 };
 
 class nsScreenManagerAndroid :
     public nsIScreenManager
 {
 public:
     nsScreenManagerAndroid();
     ~nsScreenManagerAndroid();

--- a/widget/cocoa/nsScreenCocoa.h
+++ b/widget/cocoa/nsScreenCocoa.h
@@ -36,28 +36,27 @@
  *
  * ***** END LICENSE BLOCK ***** */
 
 #ifndef nsScreenCocoa_h_
 #define nsScreenCocoa_h_
 
 #import <Cocoa/Cocoa.h>
 
-#include "nsBaseScreen.h"
+#include "nsIScreen.h"
 
-class nsScreenCocoa : public nsBaseScreen
+class nsScreenCocoa : public nsIScreen
 {
 public:
     nsScreenCocoa (NSScreen *screen);
     ~nsScreenCocoa ();
 
-    NS_IMETHOD GetRect(PRInt32* aLeft, PRInt32* aTop, PRInt32* aWidth, PRInt32* aHeight);
-    NS_IMETHOD GetAvailRect(PRInt32* aLeft, PRInt32* aTop, PRInt32* aWidth, PRInt32* aHeight);
-    NS_IMETHOD GetPixelDepth(PRInt32* aPixelDepth);
-    NS_IMETHOD GetColorDepth(PRInt32* aColorDepth);
+    NS_DECL_ISUPPORTS
+
+    NS_DECL_NSISCREEN
 
     NSScreen *CocoaScreen() { return mScreen; }
 
 private:
     NSScreen *mScreen;
 };
 
 #endif // nsScreenCocoa_h_

--- a/widget/cocoa/nsScreenCocoa.mm
+++ b/widget/cocoa/nsScreenCocoa.mm
@@ -35,16 +35,18 @@
  * the terms of any one of the MPL, the GPL or the LGPL.
  *
  * ***** END LICENSE BLOCK ***** */
 
 #include "nsScreenCocoa.h"
 #include "nsObjCExceptions.h"
 #include "nsCocoaUtils.h"
 
+NS_IMPL_ISUPPORTS1(nsScreenCocoa, nsIScreen)
+
 nsScreenCocoa::nsScreenCocoa (NSScreen *screen)
 {
   NS_OBJC_BEGIN_TRY_ABORT_BLOCK;
 
   mScreen = [screen retain];
 
   NS_OBJC_END_TRY_ABORT_BLOCK;
 }

--- a/widget/gonk/nsScreenManagerGonk.cpp
+++ b/widget/gonk/nsScreenManagerGonk.cpp
@@ -36,16 +36,18 @@
  *
  * ***** END LICENSE BLOCK ***** */
 
 #include "nsScreenManagerGonk.h"
 #include "nsWindow.h"
 
 using namespace mozilla;
 
+NS_IMPL_ISUPPORTS2(nsScreenGonk, nsIScreen, nsIScreen)
+
 nsScreenGonk::nsScreenGonk(void *nativeScreen)
 {
 }
 
 nsScreenGonk::~nsScreenGonk()
 {
 }
 
@@ -57,33 +59,36 @@ nsScreenGonk::GetRect(PRInt32 *outLeft, 
     *outTop = gScreenBounds.y;
 
     *outWidth = gScreenBounds.width;
     *outHeight = gScreenBounds.height;
 
     return NS_OK;
 }
 
+
 NS_IMETHODIMP
 nsScreenGonk::GetAvailRect(PRInt32 *outLeft,  PRInt32 *outTop,
-                           PRInt32 *outWidth, PRInt32 *outHeight)
+                          PRInt32 *outWidth, PRInt32 *outHeight)
 {
     return GetRect(outLeft, outTop, outWidth, outHeight);
 }
 
 
+
 NS_IMETHODIMP
 nsScreenGonk::GetPixelDepth(PRInt32 *aPixelDepth)
 {
     // XXX do we need to lie here about 16bpp?  Or
     // should we actually check and return the right thing?
     *aPixelDepth = 24;
     return NS_OK;
 }
 
+
 NS_IMETHODIMP
 nsScreenGonk::GetColorDepth(PRInt32 *aColorDepth)
 {
     return GetPixelDepth(aColorDepth);
 }
 
 NS_IMPL_ISUPPORTS1(nsScreenManagerGonk, nsIScreenManager)
 

--- a/widget/gonk/nsScreenManagerGonk.h
+++ b/widget/gonk/nsScreenManagerGonk.h
@@ -36,29 +36,28 @@
  *
  * ***** END LICENSE BLOCK ***** */
 
 #ifndef nsScreenManagerGonk_h___
 #define nsScreenManagerGonk_h___
 
 #include "nsCOMPtr.h"
 
-#include "nsBaseScreen.h"
 #include "nsIScreenManager.h"
+#include "nsIScreen.h"
+#include "WidgetUtils.h"
 
-class nsScreenGonk : public nsBaseScreen
+class nsScreenGonk : public nsIScreen
 {
 public:
-    nsScreenGonk(void* nativeScreen);
+    nsScreenGonk(void *nativeScreen);
     ~nsScreenGonk();
 
-    NS_IMETHOD GetRect(PRInt32* aLeft, PRInt32* aTop, PRInt32* aWidth, PRInt32* aHeight);
-    NS_IMETHOD GetAvailRect(PRInt32* aLeft, PRInt32* aTop, PRInt32* aWidth, PRInt32* aHeight);
-    NS_IMETHOD GetPixelDepth(PRInt32* aPixelDepth);
-    NS_IMETHOD GetColorDepth(PRInt32* aColorDepth);
+    NS_DECL_ISUPPORTS
+    NS_DECL_NSISCREEN
 };
 
 class nsScreenManagerGonk : public nsIScreenManager
 {
 public:
     nsScreenManagerGonk();
     ~nsScreenManagerGonk();
 

--- a/widget/gtk2/nsScreenGtk.cpp
+++ b/widget/gtk2/nsScreenGtk.cpp
@@ -53,16 +53,20 @@ nsScreenGtk :: nsScreenGtk (  )
 }
 
 
 nsScreenGtk :: ~nsScreenGtk()
 {
 }
 
 
+// addref, release, QI
+NS_IMPL_ISUPPORTS1(nsScreenGtk, nsIScreen)
+
+
 NS_IMETHODIMP
 nsScreenGtk :: GetRect(PRInt32 *outLeft, PRInt32 *outTop, PRInt32 *outWidth, PRInt32 *outHeight)
 {
   *outLeft = mRect.x;
   *outTop = mRect.y;
   *outWidth = mRect.width;
   *outHeight = mRect.height;
 

--- a/widget/gtk2/nsScreenGtk.h
+++ b/widget/gtk2/nsScreenGtk.h
@@ -33,17 +33,17 @@
  * the provisions above, a recipient may use your version of this file under
  * the terms of any one of the MPL, the GPL or the LGPL.
  *
  * ***** END LICENSE BLOCK ***** */
 
 #ifndef nsScreenGtk_h___
 #define nsScreenGtk_h___
 
-#include "nsBaseScreen.h"
+#include "nsIScreen.h"
 #include "nsRect.h"
 #include "gdk/gdk.h"
 #ifdef MOZ_X11
 #include <X11/Xlib.h>
 
 // from Xinerama.h
 typedef struct {
    int   screen_number;
@@ -51,26 +51,24 @@ typedef struct {
    short y_org;
    short width;
    short height;
 } XineramaScreenInfo;
 #endif /* MOZ_X11 */
 
 //------------------------------------------------------------------------
 
-class nsScreenGtk : public nsBaseScreen
+class nsScreenGtk : public nsIScreen
 {
 public:
   nsScreenGtk();
   ~nsScreenGtk();
 
-  NS_IMETHOD GetRect(PRInt32* aLeft, PRInt32* aTop, PRInt32* aWidth, PRInt32* aHeight);
-  NS_IMETHOD GetAvailRect(PRInt32* aLeft, PRInt32* aTop, PRInt32* aWidth, PRInt32* aHeight);
-  NS_IMETHOD GetPixelDepth(PRInt32* aPixelDepth);
-  NS_IMETHOD GetColorDepth(PRInt32* aColorDepth);
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSISCREEN
 
   void Init(GdkWindow *aRootWindow);
 #ifdef MOZ_X11
   void Init(XineramaScreenInfo *aScreenInfo);
 #endif /* MOZ_X11 */
 
 private:
   PRUint32 mScreenNum;

--- a/widget/nsIScreen.idl
+++ b/widget/nsIScreen.idl
@@ -33,31 +33,43 @@
  * and other provisions required by the GPL or the LGPL. If you do not delete
  * the provisions above, a recipient may use your version of this file under
  * the terms of any one of the MPL, the GPL or the LGPL.
  *
  * ***** END LICENSE BLOCK ***** */
 
 #include "nsISupports.idl"
 
-[scriptable, uuid(498dcd6c-94a2-4c32-8c77-531b583dff37)]
+
+[scriptable, uuid(f728830e-1dd1-11b2-9598-fb9f414f2465)]
 interface nsIScreen : nsISupports
 {
+  void GetRect ( out long left, out long top, out long width, out long height );
+  void GetAvailRect ( out long left, out long top, out long width, out long height );
+  
+  readonly attribute long pixelDepth;
+  readonly attribute long colorDepth;  
+};
+
+
+%{ C++
+
+%}
+
+[scriptable, uuid(f7c93d20-c4e4-4628-b343-cb5530b04f15)]
+interface nsIScreen_MOZILLA_2_0_BRANCH : nsISupports {
   /**
    * Levels of brightness for the screen, from off to full brightness.
    */
   const unsigned long BRIGHTNESS_DIM = 0;
   const unsigned long BRIGHTNESS_FULL = 1;
 
   /* The number of different brightness levels */
   const unsigned long BRIGHTNESS_LEVELS = 2;
 
-  void getRect(out long left, out long top, out long width, out long height);
-  void getAvailRect(out long left, out long top, out long width, out long height);
-
   /**
    * Locks the minimum brightness of the screen, forcing it to be at
    * least as bright as a certain brightness level. Each call to this
    * function must eventually be followed by a corresponding call to
    * unlockMinimumBrightness, with the same brightness level.
    *
    * @param brightness A brightness level, one of the above constants.
    */
@@ -65,12 +77,10 @@ interface nsIScreen : nsISupports
 
   /**
    * Releases a lock on the screen brightness. This must be called
    * (eventually) after a corresponding call to lockMinimumBrightness.
    *
    * @param brightness A brightness level, one of the above constants.
    */
   void unlockMinimumBrightness(in unsigned long brightness);
-  
-  readonly attribute long pixelDepth;
-  readonly attribute long colorDepth;  
 };
+

--- a/widget/os2/nsScreenOS2.cpp
+++ b/widget/os2/nsScreenOS2.cpp
@@ -46,16 +46,20 @@ nsScreenOS2 :: nsScreenOS2 (  )
 
 
 nsScreenOS2 :: ~nsScreenOS2()
 {
   // nothing to see here.
 }
 
 
+// addref, release, QI
+NS_IMPL_ISUPPORTS1(nsScreenOS2, nsIScreen)
+
+
 NS_IMETHODIMP
 nsScreenOS2 :: GetRect(PRInt32 *outLeft, PRInt32 *outTop, PRInt32 *outWidth, PRInt32 *outHeight)
 {
   LONG alArray[2];
 
   HPS hps = ::WinGetScreenPS( HWND_DESKTOP);
   HDC hdc = ::GpiQueryDevice (hps);
   ::DevQueryCaps(hdc, CAPS_WIDTH, 2, alArray);

--- a/widget/os2/nsScreenOS2.h
+++ b/widget/os2/nsScreenOS2.h
@@ -33,32 +33,30 @@
  * the provisions above, a recipient may use your version of this file under
  * the terms of any one of the MPL, the GPL or the LGPL.
  *
  * ***** END LICENSE BLOCK ***** */
 
 #ifndef nsScreenOS2_h___
 #define nsScreenOS2_h___
 
-#include "nsBaseScreen.h"
+#include "nsIScreen.h"
 
 #define INCL_WIN
 #define INCL_DOS
 #include <os2.h>
 
 //------------------------------------------------------------------------
 
-class nsScreenOS2 : public nsBaseScreen
+class nsScreenOS2 : public nsIScreen
 {
 public:
   nsScreenOS2 ( );
   virtual ~nsScreenOS2();
 
-  NS_IMETHOD GetRect(PRInt32* aLeft, PRInt32* aTop, PRInt32* aWidth, PRInt32* aHeight);
-  NS_IMETHOD GetAvailRect(PRInt32* aLeft, PRInt32* aTop, PRInt32* aWidth, PRInt32* aHeight);
-  NS_IMETHOD GetPixelDepth(PRInt32* aPixelDepth);
-  NS_IMETHOD GetColorDepth(PRInt32* aColorDepth);
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSISCREEN
 
 private:
 
 };
 
 #endif  // nsScreenOS2_h___ 

--- a/widget/qt/nsScreenQt.cpp
+++ b/widget/qt/nsScreenQt.cpp
@@ -74,16 +74,23 @@ nsScreenQt::nsScreenQt(int aScreen)
 nsScreenQt::~nsScreenQt()
 {
 #ifdef MOZ_ENABLE_QMSYSTEM2
     delete mDisplayState;
     mDisplayState = nsnull;
 #endif
 }
 
+// addref, release, QI
+#ifdef MOZ_ENABLE_QMSYSTEM2
+NS_IMPL_ISUPPORTS2(nsScreenQt, nsIScreen, nsIScreen_MOZILLA_2_0_BRANCH)
+#else
+NS_IMPL_ISUPPORTS1(nsScreenQt, nsIScreen)
+#endif
+
 NS_IMETHODIMP
 nsScreenQt::GetRect(PRInt32 *outLeft,PRInt32 *outTop,
                     PRInt32 *outWidth,PRInt32 *outHeight)
 {
     QRect r = QApplication::desktop()->screenGeometry(mScreen);
 #ifdef MOZ_ENABLE_QTMOBILITY
     r = MozQOrientationSensorFilter::GetRotationTransform().mapRect(r);
     // just rotating gives us weird negative coordinates, but we want to return

--- a/widget/qt/nsScreenQt.h
+++ b/widget/qt/nsScreenQt.h
@@ -36,42 +36,43 @@
  * the provisions above, a recipient may use your version of this file under
  * the terms of any one of the MPL, the GPL or the LGPL.
  *
  * ***** END LICENSE BLOCK ***** */
 
 #ifndef nsScreenQt_h___
 #define nsScreenQt_h___
 
-#include "nsBaseScreen.h"
+#include "nsIScreen.h"
 
 #ifdef MOZ_ENABLE_QMSYSTEM2
+#include "WidgetUtils.h"
 namespace MeeGo
 {
     class QmDisplayState;
 }
 #endif
 
 
 //------------------------------------------------------------------------
 
-class nsScreenQt : public nsBaseScreen
+class nsScreenQt : public nsIScreen
+#ifdef MOZ_ENABLE_QMSYSTEM2
+                , public mozilla::widget::BrightnessLockingWidget
+#endif
 {
 public:
   nsScreenQt (int aScreen);
   virtual ~nsScreenQt();
 
-  NS_IMETHOD GetRect(PRInt32* aLeft, PRInt32* aTop, PRInt32* aWidth, PRInt32* aHeight);
-  NS_IMETHOD GetAvailRect(PRInt32* aLeft, PRInt32* aTop, PRInt32* aWidth, PRInt32* aHeight);
-  NS_IMETHOD GetPixelDepth(PRInt32* aPixelDepth);
-  NS_IMETHOD GetColorDepth(PRInt32* aColorDepth);
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSISCREEN
 
 #ifdef MOZ_ENABLE_QMSYSTEM2
-protected:
-  virtual void ApplyMinimumBrightness(PRUint32 aType) MOZ_OVERRIDE;
+  void ApplyMinimumBrightness(PRUint32 aType);
 private:
   MeeGo::QmDisplayState* mDisplayState;
 #endif
 private:
   int mScreen;
 };
 
 #endif  // nsScreenQt_h___

--- a/widget/shared/WidgetUtils.cpp
+++ b/widget/shared/WidgetUtils.cpp
@@ -75,10 +75,59 @@ WidgetUtils::DOMWindowToWidget(nsIDOMWin
         baseWin = do_QueryInterface(window->GetDocShell());
       }
     }
   }
 
   return widget.forget();
 }
 
+// class BrightnessLockingWidget
+
+BrightnessLockingWidget::BrightnessLockingWidget()
+{
+  for (PRUint32 i = 0; i < nsIScreen_MOZILLA_2_0_BRANCH::BRIGHTNESS_LEVELS; i++)
+    mBrightnessLocks[i] = 0;
+}
+
+NS_IMETHODIMP
+BrightnessLockingWidget::LockMinimumBrightness(PRUint32 aBrightness)
+{
+  NS_ABORT_IF_FALSE(
+    aBrightness < nsIScreen_MOZILLA_2_0_BRANCH::BRIGHTNESS_LEVELS,
+    "Invalid brightness level to lock");
+  mBrightnessLocks[aBrightness]++;
+  NS_ABORT_IF_FALSE(mBrightnessLocks[aBrightness] > 0,
+    "Overflow after locking brightness level");
+
+  CheckMinimumBrightness();
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+BrightnessLockingWidget::UnlockMinimumBrightness(PRUint32 aBrightness)
+{
+  NS_ABORT_IF_FALSE(
+    aBrightness < nsIScreen_MOZILLA_2_0_BRANCH::BRIGHTNESS_LEVELS,
+    "Invalid brightness level to lock");
+  NS_ABORT_IF_FALSE(mBrightnessLocks[aBrightness] > 0,
+    "Unlocking a brightness level with no corresponding lock");
+  mBrightnessLocks[aBrightness]--;
+
+  CheckMinimumBrightness();
+
+  return NS_OK;
+}
+
+void
+BrightnessLockingWidget::CheckMinimumBrightness()
+{
+  PRUint32 brightness = nsIScreen_MOZILLA_2_0_BRANCH::BRIGHTNESS_LEVELS;
+  for (PRUint32 i = 0; i < nsIScreen_MOZILLA_2_0_BRANCH::BRIGHTNESS_LEVELS; i++)
+    if (mBrightnessLocks[i] > 0)
+      brightness = i;
+
+  ApplyMinimumBrightness(brightness);
+}
+
 } // namespace widget
 } // namespace mozilla

--- a/widget/shared/WidgetUtils.h
+++ b/widget/shared/WidgetUtils.h
@@ -40,27 +40,68 @@
 
 #ifndef __mozilla_widget_WidgetUtils_h__
 #define __mozilla_widget_WidgetUtils_h__
 
 #include "nsCOMPtr.h"
 #include "nsIWidget.h"
 #include "nsPIDOMWindow.h"
 #include "nsIDOMWindow.h"
+#include "nsIScreen.h"
 
 namespace mozilla {
 namespace widget {
 
 class WidgetUtils
 {
 public:
 
   /**
    * Starting at the docshell item for the passed in DOM window this looks up
    * the docshell tree until it finds a docshell item that has a widget.
    */
   static already_AddRefed<nsIWidget> DOMWindowToWidget(nsIDOMWindow *aDOMWindow);
 };
 
+/**
+ * Simple management of screen brightness locks. This abstract base class
+ * allows all widget implementations to share brightness locking code.
+ */
+class BrightnessLockingWidget : public nsIScreen_MOZILLA_2_0_BRANCH
+{
+public:
+  BrightnessLockingWidget();
+
+  NS_IMETHOD LockMinimumBrightness(PRUint32 aBrightness);
+  NS_IMETHOD UnlockMinimumBrightness(PRUint32 aBrightness);
+
+protected:
+  /**
+   * Manually set the current level of brightness locking. This is called after
+   * we determine, based on the current active locks, what the strongest
+   * lock is. You should normally not call this function - it will be
+   * called automatically by this class.
+   *
+   * Each widget implementation should implement this in a way that
+   * makes sense there. This is normally the only function that
+   * contains widget-specific code.
+   *
+   * @param aBrightness The current brightness level to set. If this is
+   *                    nsIScreen_MOZILLA_2_0_BRANCH::BRIGHTNESS_LEVELS
+   *                    (an impossible value for a brightness level to be),
+   *                    then that signifies that there is no current
+   *                    minimum brightness level, and the screen can shut off.
+   */
+  virtual void ApplyMinimumBrightness(PRUint32 aBrightness) = 0;
+
+  /**
+   * Checks what the minimum brightness value is, and calls
+   * ApplyMinimumBrightness.
+   */
+  void CheckMinimumBrightness();
+
+  PRUint32 mBrightnessLocks[nsIScreen_MOZILLA_2_0_BRANCH::BRIGHTNESS_LEVELS];
+};
+
 } // namespace widget
 } // namespace mozilla
 
 #endif

--- a/widget/windows/nsScreenWin.cpp
+++ b/widget/windows/nsScreenWin.cpp
@@ -65,16 +65,20 @@ nsScreenWin :: nsScreenWin ( void* inScr
 
 
 nsScreenWin :: ~nsScreenWin()
 {
   // nothing to see here.
 }
 
 
+// addref, release, QI
+NS_IMPL_ISUPPORTS1(nsScreenWin, nsIScreen)
+
+
 NS_IMETHODIMP
 nsScreenWin :: GetRect(PRInt32 *outLeft, PRInt32 *outTop, PRInt32 *outWidth, PRInt32 *outHeight)
 {
   BOOL success = FALSE;
 #if _MSC_VER >= 1200
   if ( mScreen ) {
     MONITORINFO info;
     info.cbSize = sizeof(MONITORINFO);

--- a/widget/windows/nsScreenWin.h
+++ b/widget/windows/nsScreenWin.h
@@ -34,29 +34,27 @@
  * the terms of any one of the MPL, the GPL or the LGPL.
  *
  * ***** END LICENSE BLOCK ***** */
 
 #ifndef nsScreenWin_h___
 #define nsScreenWin_h___
 
 #include <windows.h>
-#include "nsBaseScreen.h"
+#include "nsIScreen.h"
 
 //------------------------------------------------------------------------
 
-class nsScreenWin : public nsBaseScreen
+class nsScreenWin : public nsIScreen
 {
 public:
   nsScreenWin ( void* inScreen );
   ~nsScreenWin();
 
-  NS_IMETHOD GetRect(PRInt32* aLeft, PRInt32* aTop, PRInt32* aWidth, PRInt32* aHeight);
-  NS_IMETHOD GetAvailRect(PRInt32* aLeft, PRInt32* aTop, PRInt32* aWidth, PRInt32* aHeight);
-  NS_IMETHOD GetPixelDepth(PRInt32* aPixelDepth);
-  NS_IMETHOD GetColorDepth(PRInt32* aColorDepth);
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSISCREEN
 
 private:
 
   void* mScreen;                    // a |HMONITOR|, can't use this type in header file though.
 };
 
 #endif  // nsScreenWin_h___ 

--- a/widget/xpwidgets/Makefile.in
+++ b/widget/xpwidgets/Makefile.in
@@ -52,17 +52,16 @@ EXPORTS = \
 
 DEFINES += \
   -D_IMPL_NS_WIDGET \
   -DNO_NSPR_10_SUPPORT=1 \
   $(NULL)
 
 CPPSRCS		= \
 		nsBaseAppShell.cpp \
-		nsBaseScreen.cpp \
 		nsBaseWidget.cpp \
 		nsTransferable.cpp \
 		nsHTMLFormatConverter.cpp \
 		nsBaseDragService.cpp \
 		nsPrimitiveHelpers.cpp \
 		nsXPLookAndFeel.cpp \
 		nsClipboardHelper.cpp \
 		nsPrintOptionsImpl.cpp \

deleted file mode 100644
--- a/widget/xpwidgets/nsBaseScreen.cpp
+++ /dev/null
@@ -1,92 +0,0 @@
-/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
- * vim: sw=2 ts=8 et :
- */
-/* ***** BEGIN LICENSE BLOCK *****
- * Version: MPL 1.1/GPL 2.0/LGPL 2.1
- *
- * The contents of this file are subject to the Mozilla Public License Version
- * 1.1 (the "License"); you may not use this file except in compliance with
- * the License. You may obtain a copy of the License at:
- * http://www.mozilla.org/MPL/
- *
- * Software distributed under the License is distributed on an "AS IS" basis,
- * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
- * for the specific language governing rights and limitations under the
- * License.
- *
- * The Original Code is Mozilla Code.
- *
- * The Initial Developer of the Original Code is
- *   The Mozilla Foundation
- * Portions created by the Initial Developer are Copyright (C) 2011
- * the Initial Developer. All Rights Reserved.
- *
- * Contributor(s):
- *   Chris Jones <jones.chris.g@gmail.com>
- *
- * Alternatively, the contents of this file may be used under the terms of
- * either the GNU General Public License Version 2 or later (the "GPL"), or
- * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
- * in which case the provisions of the GPL or the LGPL are applicable instead
- * of those above. If you wish to allow use of your version of this file only
- * under the terms of either the GPL or the LGPL, and not to allow others to
- * use your version of this file under the terms of the MPL, indicate your
- * decision by deleting the provisions above and replace them with the notice
- * and other provisions required by the GPL or the LGPL. If you do not delete
- * the provisions above, a recipient may use your version of this file under
- * the terms of any one of the MPL, the GPL or the LGPL.
- *
- * ***** END LICENSE BLOCK ***** */
-
-#include "nsBaseScreen.h"
-
-NS_IMPL_ISUPPORTS1(nsBaseScreen, nsIScreen)
-
-nsBaseScreen::nsBaseScreen()
-{
-  for (PRUint32 i = 0; i < nsIScreen::BRIGHTNESS_LEVELS; i++)
-    mBrightnessLocks[i] = 0;
-}
-
-nsBaseScreen::~nsBaseScreen() { }
-
-NS_IMETHODIMP
-nsBaseScreen::LockMinimumBrightness(PRUint32 aBrightness)
-{
-  NS_ABORT_IF_FALSE(
-    aBrightness < nsIScreen::BRIGHTNESS_LEVELS,
-    "Invalid brightness level to lock");
-  mBrightnessLocks[aBrightness]++;
-  NS_ABORT_IF_FALSE(mBrightnessLocks[aBrightness] > 0,
-    "Overflow after locking brightness level");
-
-  CheckMinimumBrightness();
-
-  return NS_OK;
-}
-
-NS_IMETHODIMP
-nsBaseScreen::UnlockMinimumBrightness(PRUint32 aBrightness)
-{
-  NS_ABORT_IF_FALSE(
-    aBrightness < nsIScreen::BRIGHTNESS_LEVELS,
-    "Invalid brightness level to lock");
-  NS_ABORT_IF_FALSE(mBrightnessLocks[aBrightness] > 0,
-    "Unlocking a brightness level with no corresponding lock");
-  mBrightnessLocks[aBrightness]--;
-
-  CheckMinimumBrightness();
-
-  return NS_OK;
-}
-
-void
-nsBaseScreen::CheckMinimumBrightness()
-{
-  PRUint32 brightness = nsIScreen::BRIGHTNESS_LEVELS;
-  for (PRUint32 i = 0; i < nsIScreen::BRIGHTNESS_LEVELS; i++)
-    if (mBrightnessLocks[i] > 0)
-      brightness = i;
-
-  ApplyMinimumBrightness(brightness);
-}

deleted file mode 100644
--- a/widget/xpwidgets/nsBaseScreen.h
+++ /dev/null
@@ -1,95 +0,0 @@
-/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
- * vim: sw=2 ts=8 et :
- */
-/* ***** BEGIN LICENSE BLOCK *****
- * Version: MPL 1.1/GPL 2.0/LGPL 2.1
- *
- * The contents of this file are subject to the Mozilla Public License Version
- * 1.1 (the "License"); you may not use this file except in compliance with
- * the License. You may obtain a copy of the License at:
- * http://www.mozilla.org/MPL/
- *
- * Software distributed under the License is distributed on an "AS IS" basis,
- * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
- * for the specific language governing rights and limitations under the
- * License.
- *
- * The Original Code is Mozilla Code.
- *
- * The Initial Developer of the Original Code is
- *   The Mozilla Foundation
- * Portions created by the Initial Developer are Copyright (C) 2011
- * the Initial Developer. All Rights Reserved.
- *
- * Contributor(s):
- *   Chris Jones <jones.chris.g@gmail.com>
- *
- * Alternatively, the contents of this file may be used under the terms of
- * either the GNU General Public License Version 2 or later (the "GPL"), or
- * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
- * in which case the provisions of the GPL or the LGPL are applicable instead
- * of those above. If you wish to allow use of your version of this file only
- * under the terms of either the GPL or the LGPL, and not to allow others to
- * use your version of this file under the terms of the MPL, indicate your
- * decision by deleting the provisions above and replace them with the notice
- * and other provisions required by the GPL or the LGPL. If you do not delete
- * the provisions above, a recipient may use your version of this file under
- * the terms of any one of the MPL, the GPL or the LGPL.
- *
- * ***** END LICENSE BLOCK ***** */
-
-#ifndef nsBaseScreen_h
-#define nsBaseScreen_h
-
-#include "mozilla/Attributes.h"
-#include "nsIScreen.h"
-
-class nsBaseScreen : public nsIScreen
-{
-public:
-  nsBaseScreen();
-  virtual ~nsBaseScreen();
-  
-  NS_DECL_ISUPPORTS
-
-  // nsIScreen interface
-
-  /**
-   * Simple management of screen brightness locks. This abstract base class
-   * allows all widget implementations to share brightness locking code.
-   */
-  NS_IMETHOD LockMinimumBrightness(PRUint32 aBrightness);
-  NS_IMETHOD UnlockMinimumBrightness(PRUint32 aBrightness);
-
-protected:
-  /**
-   * Manually set the current level of brightness locking. This is called after
-   * we determine, based on the current active locks, what the strongest
-   * lock is. You should normally not call this function - it will be
-   * called automatically by this class.
-   *
-   * Each widget implementation should implement this in a way that
-   * makes sense there. This is normally the only function that
-   * contains widget-specific code.
-   *
-   * The default implementation does nothing.
-   *
-   * @param aBrightness The current brightness level to set. If this is
-   *                    nsIScreen_MOZILLA_2_0_BRANCH::BRIGHTNESS_LEVELS
-   *                    (an impossible value for a brightness level to be),
-   *                    then that signifies that there is no current
-   *                    minimum brightness level, and the screen can shut off.
-   */
-  virtual void ApplyMinimumBrightness(PRUint32 aBrightness) { }
-
-private:
-  /**
-   * Checks what the minimum brightness value is, and calls
-   * ApplyMinimumBrightness.
-   */
-  void CheckMinimumBrightness();
-
-  PRUint32 mBrightnessLocks[nsIScreen::BRIGHTNESS_LEVELS];
-};
-
-#endif // nsBaseScreen_h