There used to be a GTK binding for PHP. It wasn't a good idea then, and I don't see how it is now as a self-contained web app.

http://gtk.php.net/ - it was a noble effort but I think they all hit the same realization we expect and everyone walked away 4 years ago.

The only "realization" they hit was that both GTK and the port was poorly maintained in most platforms.

If it was better done and with more manpower, there would be absolutely no problem with people using it...

Can you list some native UI controls that you'd like to use but can't recreate in HTML? I am writing a similar framework and would like to know the use-cases for doing this.

Edit: besides Window and Menu, of course

You can recreate almost anything in css/html but you'd have to write a different style for each OS yourself, and it will never match the actual "feel" of the UI. It'll be a little off.

Also, for example Mac OS X has lots of little widgets like the share button.

Maybe someone could make a Bootstrap-like project for these kinds of things?

There's tint2 for doing native apps with JS.

I recently spent an afternoon trying to get a webapp to accept drag and drop emails from outlook. I didn't manage. I am considering making a native app to interact.

maybe see wxPHP [1]

[1] http://wxphp.org/

Bindings with native GUI would have been great.