We've seen these countless times before. Trying to recreate native UI in web technologies is a lost cause in my book. I think what you've got here for an OS X

We've seen these countless times before. Trying to recreate native UI in web technologies is a lost cause in my book. I think what you've got here for an OS X implementation is pretty good, but I can still tell that it isn't really native, and if an OS update changes anything in regard to the standard UI components forget about it. Why not design and develop your own UI? That way you can control how it is supposed to work given the drawbacks and advantages of web technologies and not have to ask the user for forgiveness of minor quirks in your reimplementation.