Last month Jeff Smith wrote a feature article titled How To Translate Common Design Principles To The Windows Phone. In it, he addresses some of the design principles of the Metro-style UI, which developers must master to create effective apps for the Windows Phone platform. As Smith writes in the article: "Metro not only dictates a visual design standard, but it also has several navigation standards that developers need to grasp if they want to develop applications for Windows Phone."

I followed up with Smith to ask him a few questions about Windows Phone application design.

Michael Desmond: You talk about the iPhone creating its own mobile standards that developers and designers have been quick to emulate. In that respect, is it incumbent on these developers to "unlearn" their assumptions about application design when targeting Windows Phone?

Jeff Smith: It’s not really about unlearning. It’s about thinking more about what users already experience with their operating systems on their phones. Mobile development is very new, and for its short lifespan developers were asked to create applications for iOS. Now with so many different operating systems, developers need to pay attention to the devices for which they are creating applications.

What are some of the most common design mis-steps that mobile developers tend to make?

Smith: I think one of the biggest mis-steps mobile developers tend to make is believing that applications can simply be scaled down from desktop to mobile. Most of the experience has to be rethought from the ground up to work properly for mobile.

As you note, the Metro UI is based on street and airport signage. Can you provide insight into why these types of signage were used as touchstones for the UI?

Smith: A great resource on Metro UI is the UI Design and Interaction Guide for Windows Phone available here.

Most people don’t know this but Metro is specifically based on the street signage for Seattle’s King County Metro System. According to Microsoft it is meant to encompass the following five characteristics: 1. Clean, light, open and fast; 2. Content, not chrome; 3. Integrated hardware and software; 4. World-class motion; 5. Soulful and alive.

With regard to Panorama and Pivot, can you provide insight into when one might be used over the other? Also, are there any system implications with these controls, such as system resource usage and performance, that might sway decision making?

Smith: Panorama controls are part of the core visual experience for Windows Phone, though they are not required to be used in applications. The main difference is Panoramas show hints of the next category and its contents. Pivot controls simply show you the next category, but not its contents until you swipe. I think Panoramas deliver a great experience and great visual effects, but they may not always be applicable to every application.

You just want to be sure that you use one or the other these controls; the controls are never supposed to be combined because their gesture-based navigation would contradict each other. Microsoft did a great job at creating a high performing OS, so I wouldn’t be swayed to not use either one of these great controls.