--- a/modules/libpref/src/init/all.js
+++ b/modules/libpref/src/init/all.js
@@ -1106,19 +1106,16 @@ pref("middlemouse.scrollbarPosition", fa
 // Clipboard behavior
 pref("clipboard.autocopy", false);
 
 // mouse wheel scroll transaction period of time (in milliseconds)
 pref("mousewheel.transaction.timeout", 1500);
 // mouse wheel scroll transaction is held even if the mouse cursor is moved.
 pref("mousewheel.transaction.ignoremovedelay", 100);
 
-// Macbook touchpad two finger pixel scrolling
-pref("mousewheel.enable_pixel_scrolling", true);
-
 // prefs for app level mouse wheel scrolling acceleration.
 // number of mousewheel clicks when acceleration starts
 // acceleration can be turned off if pref is set to -1
 pref("mousewheel.acceleration.start", -1);
 // factor to be multiplied for constant acceleration
 pref("mousewheel.acceleration.factor", 10);
 
 // Prefs for override the system mouse wheel scrolling speed on the root
@@ -1847,16 +1844,19 @@ pref("intl.tsf.on_layout_change_interval
 pref("ui.panel.default_level_parent", true);
 #else
 // See bug 448927, on topmost panel, some IMEs are not usable on Windows.
 pref("ui.panel.default_level_parent", false);
 #endif
 
 pref("mousewheel.system_scroll_override_on_root_content.enabled", true);
 
+// High resolution scrolling with supported mouse drivers on Vista or later.
+pref("mousewheel.enable_pixel_scrolling", false);
+
 // If your mouse drive sends WM_*SCROLL messages when you turn your mouse wheel,
 // set this to true.  Then, gecko processes them as mouse wheel messages.
 pref("mousewheel.emulate_at_wm_scroll", false);
 
 // Enables or disabled the TrackPoint hack, -1 is autodetect, 0 is off,
 // and 1 is on.  Set this to 1 if TrackPoint scrolling is not working.
 pref("ui.trackpoint_hack.enabled", -1);
 
@@ -2295,16 +2295,19 @@ pref("print.print_extra_margin", 90); //
 
 // See bug 404131, topmost <panel> element wins to Dashboard on MacOSX.
 pref("ui.panel.default_level_parent", false);
 
 pref("ui.plugin.cancel_composition_at_input_source_changed", false);
 
 pref("mousewheel.system_scroll_override_on_root_content.enabled", false);
 
+// Macbook touchpad two finger pixel scrolling
+pref("mousewheel.enable_pixel_scrolling", true);
+
 # XP_MACOSX
 #endif
 
 #ifdef XP_OS2
 
 pref("ui.key.menuAccessKeyFocuses", true);
 
 pref("font.alias-list", "sans,sans-serif,serif,monospace,Tms Rmn,Helv,Courier,Times New Roman");

--- a/widget/src/windows/nsWindow.cpp
+++ b/widget/src/windows/nsWindow.cpp
@@ -293,16 +293,17 @@ LPFNLRESULTFROMOBJECT
 
 // Used in OOPP plugin focus processing.
 const PRUnichar* kOOPPPluginFocusEventId   = L"OOPP Plugin Focus Widget Event";
 PRUint32        nsWindow::sOOPPPluginFocusEvent   =
                   RegisterWindowMessageW(kOOPPPluginFocusEventId);
 
 MSG             nsWindow::sRedirectedKeyDown;
 
+PRBool          nsWindow::sEnablePixelScrolling = PR_TRUE;
 PRBool          nsWindow::sNeedsToInitMouseWheelSettings = PR_TRUE;
 ULONG           nsWindow::sMouseWheelScrollLines  = 0;
 ULONG           nsWindow::sMouseWheelScrollChars  = 0;
 
 HWND            nsWindow::sLastMouseWheelWnd = NULL;
 PRInt32         nsWindow::sRemainingDeltaForScroll = 0;
 PRInt32         nsWindow::sRemainingDeltaForPixel = 0;
 PRBool          nsWindow::sLastMouseWheelDeltaIsPositive = PR_FALSE;
@@ -662,16 +663,21 @@ nsWindow::Create(nsIWidget *aParent,
 
         if (NS_SUCCEEDED(prefBranch->GetBoolPref("intl.keyboard.per_window_layout",
                                                  &temp)))
           sSwitchKeyboardLayout = temp;
 
         if (NS_SUCCEEDED(prefBranch->GetBoolPref("mozilla.widget.disable-native-theme",
                                                  &temp)))
           gDisableNativeTheme = temp;
+
+        if (NS_SUCCEEDED(prefBranch->GetBoolPref("mousewheel.enable_pixel_scrolling",
+                                                 &temp))) {
+          sEnablePixelScrolling = temp;
+        }
       }
     }
   }
 
   return NS_OK;
 }
 
 // Close this nsWindow
@@ -6406,37 +6412,43 @@ nsWindow::OnMouseWheel(UINT aMessage, WP
     ResetRemainingWheelDelta();
   }
   sLastMouseWheelWnd = mWnd;
   sLastMouseWheelDeltaIsPositive = (nativeDelta > 0);
   sLastMouseWheelOrientationIsVertical = isVertical;
   sLastMouseWheelUnitIsPage = isPageScroll;
   sLastMouseWheelTime = now;
 
-  nsMouseScrollEvent testEvent(PR_TRUE, NS_MOUSE_SCROLL, this);
-  InitEvent(testEvent);
-  testEvent.scrollFlags = isPageScroll ? nsMouseScrollEvent::kIsFullPage : 0;
-  testEvent.scrollFlags |= isVertical ? nsMouseScrollEvent::kIsVertical :
-                                        nsMouseScrollEvent::kIsHorizontal;
-  testEvent.delta = sLastMouseWheelDeltaIsPositive ? -1 : 1;
-  nsQueryContentEvent queryEvent(PR_TRUE, NS_QUERY_SCROLL_TARGET_INFO, this);
-  InitEvent(queryEvent);
-  queryEvent.InitForQueryScrollTargetInfo(&testEvent);
-  DispatchWindowEvent(&queryEvent);
-  // If the necessary interger isn't larger than 0, we should assume that
-  // the event failed for us.
-  if (queryEvent.mSucceeded) {
-    if (isPageScroll) {
-      if (isVertical) {
-        queryEvent.mSucceeded = (queryEvent.mReply.mPageHeight > 0);
+  PRBool dispatchPixelScrollEvent = PR_FALSE;
+  PRInt32 pixelsPerUnit = 0;
+
+  if (sEnablePixelScrolling) {
+    nsMouseScrollEvent testEvent(PR_TRUE, NS_MOUSE_SCROLL, this);
+    InitEvent(testEvent);
+    testEvent.scrollFlags = isPageScroll ? nsMouseScrollEvent::kIsFullPage : 0;
+    testEvent.scrollFlags |= isVertical ? nsMouseScrollEvent::kIsVertical :
+                                          nsMouseScrollEvent::kIsHorizontal;
+    testEvent.delta = sLastMouseWheelDeltaIsPositive ? -1 : 1;
+    nsQueryContentEvent queryEvent(PR_TRUE, NS_QUERY_SCROLL_TARGET_INFO, this);
+    InitEvent(queryEvent);
+    queryEvent.InitForQueryScrollTargetInfo(&testEvent);
+    DispatchWindowEvent(&queryEvent);
+    // If the necessary interger isn't larger than 0, we should assume that
+    // the event failed for us.
+    if (queryEvent.mSucceeded) {
+      if (isPageScroll) {
+        if (isVertical) {
+          pixelsPerUnit = queryEvent.mReply.mPageHeight;
+        } else {
+          pixelsPerUnit = queryEvent.mReply.mPageWidth;
+        }
       } else {
-        queryEvent.mSucceeded = (queryEvent.mReply.mPageWidth > 0);
+        pixelsPerUnit = queryEvent.mReply.mLineHeight;
       }
-    } else {
-      queryEvent.mSucceeded = (queryEvent.mReply.mLineHeight > 0);
+      dispatchPixelScrollEvent = (pixelsPerUnit > 0);
     }
   }
 
   *aRetValue = isVertical ? FALSE : TRUE; // means we process this message
   nsModifierKeyState modKeyState;
 
   // Our positive delta value means to bottom or right.
   // But positive nativeDelta value means to top or right.
@@ -6451,19 +6463,18 @@ nsWindow::OnMouseWheel(UINT aMessage, WP
       static_cast<DWORD>(::GetMessageTime()) < mAssumeWheelIsZoomUntil) {
     isControl = PR_TRUE;
   } else {
     isControl = modKeyState.mIsControlDown;
   }
 
   nsMouseScrollEvent scrollEvent(PR_TRUE, NS_MOUSE_SCROLL, this);
   InitEvent(scrollEvent);
-  // If the query event failed, we cannot send pixel events.
   scrollEvent.scrollFlags =
-    queryEvent.mSucceeded ? nsMouseScrollEvent::kHasPixels : 0;
+    dispatchPixelScrollEvent ? nsMouseScrollEvent::kHasPixels : 0;
   scrollEvent.isShift     = modKeyState.mIsShiftDown;
   scrollEvent.isControl   = isControl;
   scrollEvent.isMeta      = PR_FALSE;
   scrollEvent.isAlt       = modKeyState.mIsAltDown;
 
   PRInt32 nativeDeltaForScroll = nativeDelta + sRemainingDeltaForScroll;
 
   if (isPageScroll) {
@@ -6496,17 +6507,17 @@ nsWindow::OnMouseWheel(UINT aMessage, WP
     aHandled = DispatchWindowEvent(&scrollEvent);
     if (mOnDestroyCalled) {
       ResetRemainingWheelDelta();
       return PR_FALSE;
     }
   }
 
   // If the query event failed, we cannot send pixel events.
-  if (!queryEvent.mSucceeded) {
+  if (!dispatchPixelScrollEvent) {
     sRemainingDeltaForPixel = 0;
     return PR_FALSE;
   }
 
   nsMouseScrollEvent pixelEvent(PR_TRUE, NS_MOUSE_PIXEL_SCROLL, this);
   InitEvent(pixelEvent);
   pixelEvent.scrollFlags = nsMouseScrollEvent::kAllowSmoothScroll |
     (scrollEvent.scrollFlags & ~nsMouseScrollEvent::kHasPixels);
@@ -6514,28 +6525,24 @@ nsWindow::OnMouseWheel(UINT aMessage, WP
   pixelEvent.isControl   = modKeyState.mIsControlDown;
   pixelEvent.isMeta      = PR_FALSE;
   pixelEvent.isAlt       = modKeyState.mIsAltDown;
 
   PRInt32 nativeDeltaForPixel = nativeDelta + sRemainingDeltaForPixel;
 
   double deltaPerPixel;
   if (isPageScroll) {
-    if (isVertical) {
-      deltaPerPixel = (double)WHEEL_DELTA / queryEvent.mReply.mPageHeight;
-    } else {
-      deltaPerPixel = (double)WHEEL_DELTA / queryEvent.mReply.mPageWidth;
-    }
+    deltaPerPixel = (double)WHEEL_DELTA / pixelsPerUnit;
   } else {
     if (isVertical) {
       deltaPerPixel = (double)WHEEL_DELTA / sMouseWheelScrollLines;
     } else {
       deltaPerPixel = (double)WHEEL_DELTA / sMouseWheelScrollChars;
     }
-    deltaPerPixel /= queryEvent.mReply.mLineHeight;
+    deltaPerPixel /= pixelsPerUnit;
   }
   pixelEvent.delta =
     RoundDelta((double)nativeDeltaForPixel * orienter / deltaPerPixel);
   PRInt32 recomputedNativeDelta =
     (PRInt32)(pixelEvent.delta * orienter * deltaPerPixel);
   sRemainingDeltaForPixel = nativeDeltaForPixel - recomputedNativeDelta;
   if (pixelEvent.delta != 0) {
     aHandled = DispatchWindowEvent(&pixelEvent);

--- a/widget/src/windows/nsWindow.h
+++ b/widget/src/windows/nsWindow.h
@@ -611,16 +611,17 @@ protected:
   static HINSTANCE      sAccLib;
   static LPFNLRESULTFROMOBJECT sLresultFromObject;
 #endif // ACCESSIBILITY
 
   // sRedirectedKeyDown is WM_KEYDOWN message or WM_SYSKEYDOWN message which
   // was reirected to SendInput() API by OnKeyDown().
   static MSG            sRedirectedKeyDown;
 
+  static PRBool sEnablePixelScrolling;
   static PRBool sNeedsToInitMouseWheelSettings;
   static ULONG sMouseWheelScrollLines;
   static ULONG sMouseWheelScrollChars;
   static void InitMouseWheelScrollData();
 
   static HWND sLastMouseWheelWnd;
   static PRInt32 sRemainingDeltaForScroll;
   static PRInt32 sRemainingDeltaForPixel;