Is Internet Explorer 9’s HTML5 compliance a mirage?

We have been covering HTML5 compliance in Internet Explorer 9 for more than a year and a half now, a fact that you might assume implies that IE9 can handle HTML5 without so much as a hitch.

You would be wrong to think so, sadly. We recently wrote a story called “Internet Explorer 9 just beat everyone in HTML5 compliance,” which gave rise to a number of, shall we say, sharp comments. We stuck to the data that we had picked up from a big test of all the major browsers, a test that showed IE9 ahead of the competition in regards to handling HTML5. We felt that our reporting was fair.

Our view on the matter is changing slightly however, following a very interesting post we recently read on DeviantArt. For reference, the post is entitled “IE9 Tries to Implement HTML5 – Hilarity Ensues. What Can Be Done About 3 Gotchas in IE9 Beta.” That should give you an idea of what the post is about. To quote:

I just spent the past couple of days porting and debugging deviantART muro in Internet Explorer 9 beta. Microsoft announced with much fanfare that they included support for <canvas> in IE9. Unfortunately I took their word at face value and assumed that my existing HTML5 code would seamlessly start working once I changed X-UA-Compatible. Alas, I instead stared in horror at my application that appeared to be possessed by some insane daemon.

[…] Chrome, Firefox, Opera, and Safari did an amazing job of coding to the HTML5 spec. I don’t know why Microsoft couldn’t as well.

The problems that the writer points out, dealing with globalCompositeOperation, Canvas Resizing, and Limited Shadow Offset, are perhaps only of interest to developers, but the overall gist of the post has a broad potential impact: IE9 is the future browser for most of the world, and so if its HTML5 compliance is not correct, the standard will not run properly for most people.

Now, it could be that IE9 is still ‘beta’ enough that the problems that DeviantArt ran into are already corrected in an unreleased version, or will be corrected before launch, but we are not sure. We have reached out to Microsoft for comment on the matter.

Will HTML5 compliance on IE9 be complete, or a mere hack-job that Microsoft touts to assuage a portion of its critics? What do you think?