message: Added message about synthesize keyword.
diff: @@ -1001,6 +1001,7 @@ void cv::setWindowTitle(const String& winname, const String& title)
  @synthesize callback;
  @synthesize callback2;
  #else
  +// 32-bit Obj-C does not have automatic synthesize
  @synthesize slider = _slider;
  @synthesize name = _name;
  @synthesize value = _value;
  