Microsoft's Sinofsky: HTML5 doesn't mean you don't need Windows

But does an OS really need all the features of Windows to run a browser? Couldn't a leaner system enable that kind of access to the hardware for the browser?

"This is one of those things that when I look at the assertions… it sounds good and then you just start listing question after question after question." It's a similar argument to the one he's made before about the cloud not being able to replace the local OS; "There's no SD card on the browser; if you have photos sitting on the SD card you have to find a way to get at them.

"If you want to do text to speech, where is the speaker? Where is the screen? Where are the accessibility tools? Where is all the code for text to speech going to reside so the browser can work with a screen reader? What about device drivers? Look at the Windows Control Panel; it has a bunch of things, none of which are in the browser… So everything has to migrate into the browser.

"Then you need the Start menu. Then you have the window management problem, so now you need the Start menu, the control panel and the taskbar. Now you need to manage files; you can emulate that with a browser but managing tens of thousands of MP3s on my external drive is a lot easier than going through a web browser.

"What if you want to print? You need a print queue and a dialog that lets you flip pages sideways and set the kind of paper you want to use… You don't just get to delete all the code and pretend you don't have those problems."

Security in IE9

Switching gears, we asked him about that perpetual IE bugbear; security – and his answer is cautious but confident. "HTML5 does increase the 'surface area' of the browser so there could be new kinds of attacks; with any new technology there is always this cat and mouse type of game.

"We're definitely focused on upping the game on that front as well – we're more aware of the implications of adding functionality.We think we're as on top of it as we can possibly be."

And what about the continuing criticisms of IE6 and the recent funeral (to which the IE team sent flowers)? "We're completely baffled by this whole thing. We have a bunch of people who come to work every day for years in this building and we're now on our third release of a browser since IE6.

"The fact that people are still running it is their choice to make – and it's not even the choice we would want them to make!" Even leaving aside how long ago IE6 was written,he suggests the attitude to it isn't perhaps quite fair compared to other platforms (like, say, iPhone - although he's careful to name no names).

"Some elements of this conversation I find puzzling; there are mixed signals from developers. IE6 is definitely an old browser and while it has lot of quirks, none of these standards existed when IE6 came out; people get the timelines confused.

"But it's a pretty large number of people using it. We see developers raising these issues in comments on our blogs… But on the other hand when some new fancy mobile device comes out people are very quick - for some tiny group of customers that's way smaller than the number of IE6 users – to do a custom page that reformats itself.

"For even 100th the size of the audience we have, they're happy to workaround all this, they're happy to make this entire shadow site. One [platform] might be growing, the other we're trying to shrink but the difference of two orders of magnitude is there."