Fixed mouse button index for additional mouse buttons

src/video/cocoa/SDL_cocoaevents.m

@@ -201,8 +201,8 @@ Cocoa_PumpEvents(_THIS)
         case NSLeftMouseDragged:
         case NSRightMouseDragged:
         case NSOtherMouseDragged: /* usually middle mouse dragged */
-        case NSScrollWheel:
         case NSMouseMoved:
+        case NSScrollWheel:
             Cocoa_HandleMouseEvent(_this, event);
             /* Pass through to NSApp to make sure everything stays in sync */
             [NSApp sendEvent:event];

src/video/cocoa/SDL_cocoamouse.m

@@ -43,7 +43,7 @@ ConvertMouseButtonToSDL(int button)
         case 2:
             return(SDL_BUTTON_MIDDLE); /* 2 */
     }
-    return button;
+    return button+1;
 }
 
 void