From fb85e72ddca40c80fe5ac46ac6f88e51f39c61ea Mon Sep 17 00:00:00 2001
From: Boris Zbarsky <bzbarsky@mit.edu>
Date: Mon, 1 Aug 2011 13:43:23 -0400
Subject: [PATCH] Bug 669979.  Don't do zoom or history actions for momentum
 scrolls, no matter what's going on with pixel scrolling.  r=smaug,masayuki

---
 content/events/src/nsEventStateManager.cpp | 17 +++++++++--------
 content/events/test/test_bug574663.html    |  4 ++++
 2 files changed, 13 insertions(+), 8 deletions(-)

diff --git a/content/events/src/nsEventStateManager.cpp b/content/events/src/nsEventStateManager.cpp
index e1847dc17d6..22dca16de84 100644
--- a/content/events/src/nsEventStateManager.cpp
+++ b/content/events/src/nsEventStateManager.cpp
@@ -2671,14 +2671,15 @@ nsEventStateManager::ComputeWheelActionFor(nsMouseScrollEvent* aMouseEvent,
       // Do not scroll pixels when zooming
       action = -1;
     }
-  } else if (aMouseEvent->scrollFlags & nsMouseScrollEvent::kHasPixels) {
-    if (aUseSystemSettings ||
-        action == MOUSE_SCROLL_N_LINES || action == MOUSE_SCROLL_PAGE ||
-        (aMouseEvent->scrollFlags & nsMouseScrollEvent::kIsMomentum)) {
-      // Don't scroll lines when a pixel scroll event will follow.
-      // Also, don't do history scrolling or zooming for momentum scrolls.
-      action = -1;
-    }
+  } else if (((aMouseEvent->scrollFlags & nsMouseScrollEvent::kHasPixels) &&
+              (aUseSystemSettings ||
+               action == MOUSE_SCROLL_N_LINES || action == MOUSE_SCROLL_PAGE)) ||
+             ((aMouseEvent->scrollFlags & nsMouseScrollEvent::kIsMomentum) &&
+              (action == MOUSE_SCROLL_HISTORY || action == MOUSE_SCROLL_ZOOM))) {
+    // Don't scroll lines or page when a pixel scroll event will follow.
+    // Also, don't do history scrolling or zooming for momentum scrolls,
+    // no matter what's going on with pixel scrolling.
+    action = -1;
   }
 
   return action;
diff --git a/content/events/test/test_bug574663.html b/content/events/test/test_bug574663.html
index 9a36bb4df7b..bac5ef90b39 100644
--- a/content/events/test/test_bug574663.html
+++ b/content/events/test/test_bug574663.html
@@ -35,7 +35,11 @@ function sendTouchpadScrollMotion(scrollbox, direction, ctrl, momentum) {
   };
   // first a line scroll
   synthesizeMouseScroll(scrollbox, 10, 10, event, win);
+  // Then a line scroll with hasPixels set to false
+  event.hasPixels = false;
+  synthesizeMouseScroll(scrollbox, 10, 10, event, win);
   // then 5 pixel scrolls
+  event.hasPixels = true;
   event.delta *= 3;
   event.type = "MozMousePixelScroll";
   event.hasPixels = false;