--- old/src/java.desktop/macosx/classes/sun/lwawt/macosx/CPlatformResponder.java	2016-09-28 15:30:40.000000000 +0400
+++ new/src/java.desktop/macosx/classes/sun/lwawt/macosx/CPlatformResponder.java	2016-09-28 15:30:40.000000000 +0400
@@ -44,6 +44,9 @@
     private final PlatformEventNotifier eventNotifier;
     private final boolean isNpapiCallback;
     private int lastKeyPressCode = KeyEvent.VK_UNDEFINED;
+    private static final double DELTA_THRESHOLD = 0.8;
+    private double accumulatedDeltaX;
+    private double accumulatedDeltaY;
 
     CPlatformResponder(final PlatformEventNotifier eventNotifier,
                        final boolean isNpapiCallback) {
@@ -89,37 +92,65 @@
      */
     void handleScrollEvent(final int x, final int y, final int absX,
                            final int absY, final int modifierFlags,
-                           final double deltaX, final double deltaY) {
+                           final double deltaX, final double deltaY,
+                           final int scrollMask) {
         int jmodifiers = NSEvent.nsToJavaModifiers(modifierFlags);
         final boolean isShift = (jmodifiers & InputEvent.SHIFT_DOWN_MASK) != 0;
 
+        int roundDeltaX = (int) Math.round(deltaX);
+        int roundDeltaY = (int) Math.round(deltaY);
+
+        if ((scrollMask & NSEvent.SCROLL_MASK_TRACKPAD) != 0) {
+            if ((scrollMask & NSEvent.SCROLL_MASK_PHASE_BEGAN) != 0) {
+                accumulatedDeltaX = deltaX;
+                accumulatedDeltaY = deltaY;
+            } else {
+                accumulatedDeltaX += deltaX;
+                accumulatedDeltaY += deltaY;
+            }
+
+            if (Math.abs(accumulatedDeltaX) > DELTA_THRESHOLD) {
+                roundDeltaX = (int) Math.round(accumulatedDeltaX);
+                accumulatedDeltaX -= roundDeltaX;
+            }
+
+            if (Math.abs(accumulatedDeltaY) > DELTA_THRESHOLD) {
+                roundDeltaY = (int) Math.round(accumulatedDeltaY);
+                accumulatedDeltaY -= roundDeltaY;
+            }
+        } else {
+            if (roundDeltaX == 0 && deltaX != 0) {
+                roundDeltaX = deltaX > 0 ? 1 : -1;
+            }
+
+            if (roundDeltaY == 0 && deltaY != 0) {
+                roundDeltaY = deltaY > 0 ? 1 : -1;
+            }
+        }
+
         // Vertical scroll.
         if (!isShift && deltaY != 0.0) {
-            dispatchScrollEvent(x, y, absX, absY, jmodifiers, deltaY);
+            dispatchScrollEvent(x, y, absX, absY, jmodifiers, roundDeltaY, deltaY);
         }
         // Horizontal scroll or shirt+vertical scroll.
         final double delta = isShift && deltaY != 0.0 ? deltaY : deltaX;
+        final int roundDelta = isShift && roundDeltaY != 0.0 ? roundDeltaY : roundDeltaX;
         if (delta != 0.0) {
             jmodifiers |= InputEvent.SHIFT_DOWN_MASK;
-            dispatchScrollEvent(x, y, absX, absY, jmodifiers, delta);
+            dispatchScrollEvent(x, y, absX, absY, jmodifiers, roundDelta, delta);
         }
     }
 
     private void dispatchScrollEvent(final int x, final int y, final int absX,
                                      final int absY, final int modifiers,
-                                     final double delta) {
+                                     final int roundDelta, final double delta) {
         final long when = System.currentTimeMillis();
         final int scrollType = MouseWheelEvent.WHEEL_UNIT_SCROLL;
         final int scrollAmount = 1;
-        int wheelRotation = (int) delta;
-        int signum = (int) Math.signum(delta);
-        if (signum * delta < 1) {
-            wheelRotation = signum;
-        }
         // invert the wheelRotation for the peer
         eventNotifier.notifyMouseWheelEvent(when, x, y, absX, absY, modifiers,
                                             scrollType, scrollAmount,
-                                            -wheelRotation, -delta, null);
+                                            -roundDelta, -delta, null);
     }
 
     /**