Holding down shift while moving the mouse's scrollwheel on MacOS X makes the

 OS report these are "horizontal scrollwheel" events, which confuses gaming
 apps in several legitimate conditions. Now all scrollwheel events are made
 to look vertical when passed to the app.

Patch by John Knottenbelt.

 http://www.libsdl.org/pipermail/sdl/2005-March/067978.html

--HG--
extra : convert_revision : svn%3Ac70aab31-4412-0410-b14c-859654838e24/trunk%401051

src/video/quartz/SDL_QuartzEvents.m

@@ -900,10 +900,11 @@ void QZ_PumpEvents (_THIS)
                     break;
                 case NSScrollWheel:
                     if ( isInGameWin ) {
-                        float dy;
+                        float dy, dx;
                         Uint8 button;
                         dy = [ event deltaY ];
-                        if ( dy > 0.0 ) /* Scroll up */
+                        dx = [ event deltaX ];
+                        if ( dy > 0.0 || dx > 0.0 ) /* Scroll up */
                             button = SDL_BUTTON_WHEELUP;
                         else /* Scroll down */
                             button = SDL_BUTTON_WHEELDOWN;