--- old/src/macosx/classes/sun/lwawt/LWWindowPeer.java	2012-02-10 23:40:24.000000000 +0400
+++ new/src/macosx/classes/sun/lwawt/LWWindowPeer.java	2012-02-10 23:40:23.000000000 +0400
@@ -803,16 +803,20 @@
         }
 
         Point lp = targetPeer.windowToLocal(x, y, this);
+        int signum = (int) Math.signum(preciseWheelRotation);
+        if (wheelRotation == 0 && signum * wheelRotation < 1) {
+           wheelRotation = signum;
+        }
         // TODO: fill "bdata" member of AWTEvent
         // TODO: screenX/screenY
         postEvent(new MouseWheelEvent(targetPeer.getTarget(),
-                                      MouseEvent.MOUSE_WHEEL,
-                                      when, modifiers,
-                                      lp.x, lp.y,
-                                      0, 0, /* screenX, Y */
-                                      0 /* clickCount */, false /* popupTrigger */,
-                                      scrollType, scrollAmount,
-                                      wheelRotation, preciseWheelRotation));
+                MouseEvent.MOUSE_WHEEL,
+                when, modifiers,
+                lp.x, lp.y,
+                0, 0, /* screenX, Y */
+                0 /* clickCount */, false /* popupTrigger */,
+                scrollType, scrollAmount,
+                wheelRotation, preciseWheelRotation));
     }
 
     /*