--- a/widget/windows/nsWindow.cpp
+++ b/widget/windows/nsWindow.cpp
@@ -120,16 +120,18 @@
 #include "mozilla/Preferences.h"
 #include "nsISound.h"
 #include "WinTaskbar.h"
 #include "WinUtils.h"
 #include "WidgetUtils.h"
 #include "nsIWidgetListener.h"
 #include "mozilla/dom/Touch.h"
 #include "mozilla/gfx/2D.h"
+#include "nsToolkitCompsCID.h"
+#include "nsIAppStartup.h"
 #include "mozilla/WindowsVersion.h"
 
 #ifdef MOZ_ENABLE_D3D9_LAYER
 #include "LayerManagerD3D9.h"
 #endif
 
 #ifdef MOZ_ENABLE_D3D10_LAYER
 #include "LayerManagerD3D10.h"
@@ -169,16 +171,20 @@
 
 #include "nsIContent.h"
 
 #include "mozilla/HangMonitor.h"
 #include "WinIMEHandler.h"
 
 #include "npapi.h"
 
+#if !defined(SM_CONVERTIBLESLATEMODE)
+#define SM_CONVERTIBLESLATEMODE 0x2003
+#endif
+
 using namespace mozilla;
 using namespace mozilla::dom;
 using namespace mozilla::layers;
 using namespace mozilla::widget;
 
 /**************************************************************
  **************************************************************
  **
@@ -5457,16 +5463,31 @@ nsWindow::ProcessMessage(UINT msg, WPARA
           // WM_KILLFOCUS was received by the child process.
           if (sJustGotDeactivate) {
             DispatchFocusToTopLevelWindow(false);
           }
         }
       }
     }
     break;
+    case WM_SETTINGCHANGE:
+      if (IsWin8OrLater() && lParam &&
+          !wcsicmp(L"ConvertibleSlateMode", (wchar_t*)lParam)) {
+        // If we're switching into slate mode, switch to Metro for hardware
+        // that supports this feature.
+        if (GetSystemMetrics(SM_CONVERTIBLESLATEMODE) == 0) {
+          nsCOMPtr<nsIAppStartup> appStartup(do_GetService(NS_APPSTARTUP_CONTRACTID));
+          if (appStartup) {
+            appStartup->Quit(nsIAppStartup::eForceQuit |
+                             nsIAppStartup::eRestartTouchEnvironment);
+          }
+        }
+      }
+    break;
+
   }
 
   //*aRetValue = result;
   if (mWnd) {
     return result;
   }
   else {
     //Events which caused mWnd destruction and aren't consumed

--- a/widget/windows/winrt/MetroWidget.cpp
+++ b/widget/windows/winrt/MetroWidget.cpp
@@ -55,16 +55,20 @@ using namespace ABI::Windows::UI::Core;
 using namespace ABI::Windows::System;
 using namespace ABI::Windows::Foundation;
 using namespace ABI::Windows::Graphics::Display;
 
 #ifdef PR_LOGGING
 extern PRLogModuleInfo* gWindowsLog;
 #endif
 
+#if !defined(SM_CONVERTIBLESLATEMODE)
+#define SM_CONVERTIBLESLATEMODE 0x2003
+#endif
+
 static uint32_t gInstanceCount = 0;
 const PRUnichar* kMetroSubclassThisProp = L"MetroSubclassThisProp";
 HWND MetroWidget::sICoreHwnd = nullptr;
 
 namespace mozilla {
 namespace widget {
 UINT sDefaultBrowserMsgId = RegisterWindowMessageW(L"DefaultBrowserClosing");
 } }
@@ -705,16 +709,27 @@ MetroWidget::StaticWindowProcedure(HWND 
   return self->WindowProcedure(aWnd, aMsg, aWParam, aLParam);
 }
 
 LRESULT
 MetroWidget::WindowProcedure(HWND aWnd, UINT aMsg, WPARAM aWParam, LPARAM aLParam)
 {
   if(sDefaultBrowserMsgId == aMsg) {
     CloseGesture();
+  } else if (WM_SETTINGCHANGE == aMsg) {
+    if (aLParam && !wcsicmp(L"ConvertibleSlateMode", (wchar_t*)aLParam)) {
+      // If we're switching away from slate mode, switch to Desktop for
+      // hardware that supports this feature.
+      if (GetSystemMetrics(SM_CONVERTIBLESLATEMODE) != 0) {
+        nsCOMPtr<nsIAppStartup> appStartup(do_GetService(NS_APPSTARTUP_CONTRACTID));
+        if (appStartup) {
+          appStartup->Quit(nsIAppStartup::eForceQuit | nsIAppStartup::eRestart);
+        }
+      }
+    }
   }
 
   // Indicates if we should hand messages to the default windows
   // procedure for processing.
   bool processDefault = true;
 
   // The result returned if we do not do default processing.
   LRESULT processResult = 0;