Turns out, this isn’t that silly question after all!
I have made some additional tests today, and it seems, that using old, XHTML way of <input autofocus=“autofocus”> works just fine. Includning IE11! I simply cannot tell you, what I did yesterday, that I didn’t see this? Code-ghosts or something.
I thought, that if “readonly” and “disabled” attributes were only back-ported to HTML5 from HTML4/XHTML, they’re respected in all possible ways. But, there was no “autofocus” before HTML5 and basing on this, I incorrectly assumed, that this will work only in HTML5-way of <input autofocus>.
That is not possible. CHtml is called internally by many of my extensions. In the mentioned situation, I’m using Yii Booster 3 to render all form elements in my application. I’d have to resign using Yii Booster at all or would have to rewrite most of its components.
Have you been using Yii-Booster or any other Twitter Bootstrap clone for Yii? It introduces a lot of changes, how forms are constructed, form elements used etc. to bring you all the goodies you have from Twitter Bootstrap. It isn’t an easy way (nor it isn’t advised) to mix CHtml methods (and form elements rendered this way) with Yii-Booster methods (and form elements this way). Not only this would have some strange implications to the code (Booster form elements and other widgets are constructed different way, using different data sets), but also it would look ugly (mixing Twitter Bootstrap-styled form elements with those rendered by CHtml).
So, while technically you’re of course right, overall effect isn’t acceptable by me. But, thanks for trying to help!