Another design consideration developers will have to grapple with is a new form of input, namely touch, where users interact with the OS directly through the display. "We really want developers to have a touch-centric approach to their applications," said Jeff Burtoft, a Microsoft HTML5 evangelist, during another talk.

Just as the mouse introduced new ways of interacting with graphical programs, so too does the touch interface offer new possibilities for user interaction. Windows 8 can determine if the device it's runs on accepts touch as an input. If it does, it activates "listeners" for touch-based input.

"All of our navigation works with both touch and mouse," Burtoft said. "If you design for touch, you get mouse for free."

Touch interactions fall into two forms: pointers and gestures.

A gesture summarizes a user's intention, such as a tap on a screen that indicates the desire to open a program. Windows 8 interprets a range of gestures on behalf of the application, so the developer doesn't have to write that code from scratch.