"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.
Microsoft developed a set of gestures, which Burtoft called the Windows 8 Touch Language, that the company wants developers to use uniformly across all their applications. The gestures include tap, press-and-hold, pinch-and-zoom, and swipe-from-the-edge. "As long as different applications all use this same language, it will be easy for users to catch on" to how to navigate through their apps, Burtoft said.
For cases where gestures can't provide the detail an application needs, Microsoft also provides pointers. With pointers, every touch point on the screen gets its own "event object," which developers can link to directly with their application code. Pointers allow the user to execute tasks such as drawing or writing on the screen.
Another aspect to consider is design. In another Build session, Microsoft's principal user experience adviser, Will Tschumy, explained the philosophy behind the new Windows, in the hope that developers will build their apps in a similar way.
To the casual observer, the new interface appears less cluttered with boxes and menu choices. This look, said Tschumy, was actually inspired by high modernism, a school of design that has its roots in the Bauhaus art movement of the early 20th century.
"It's all about trying to get the OS out of the way," he said. Windows 8 tries to help users focus on the task, he said. Apps should have very little, if any, chrome -- the design term for boxes and menu selections that frame most applications today. Instead, the content of the application, such as a photo, video or text document, should take up the entire screen.
Tschumy advised developers that, whenever they have a design question with Windows 8, they should think "content before chrome."
One company embracing the new design paradigm is SAP. The ERP (enterprise-resource-planning) vendor plans to release six applications in the next few months that embrace the new Windows design rules, said Fred Samson, SAP vice president of mobility and innovation, in another session.
"We tried to leverage as many Windows 8 features as we can," Samson said. The new interface allows SAP to build applications that are more immersive and interactive, he said. Users can move about a document by scrolling rather than paging, data can be displayed on maps instead of lists, and documents can be identified by images instead of names.