First steps with Windows 8 development - Build Windows 8 Apps with HTML5 and JavaScript - page 106

Zero redundancy
For many years, redundancy in the user interface of an application has been considered a good thing.
You define a user interface as redundant if it allows performing the same task in more than one way.
Keyboard and mouse navigation, slightly different menu items (such as, Save, Save All, Save As), and
keyboard shortcuts all produce the same result in many applications you may use currently.
In a user interface that is essentially touch-based, all these methods have no reason to exist.
Subsequently, the zero redundancy policy is a great virtue of Windows Store applications.
This is a design consideration that also emerges quite clearly in many successful mobile
applications and is tightly connected to a growing need for simplicity and effectiveness—like being
able to do more things (or just the same things) with less options and less tools.
Do as romans do
Another pillar of software development of the past that the Windows 8 UI brings into question is
the overall user interface model. For various reasons, some applications made a point of providing a
custom user interface. Sometimes this has happened to make the application shine in comparison to
other applications of the same type. Sometimes, instead, it came as the result of trying to make the
application in some way more usable and enjoyable.
Any application in Windows 8 should take its own space in the context of the user interface
model dictated by the platform. For this reason, the fourth principle of Windows 8 applications can
be summarized with the old proverb that suggests doing as Romans do, at least when you're in
Rome. Also, this principle is nothing new to anybody with a bit of experience in mobile application
development.
Especially in iOS and Windows Phone markets, applications may be rejected if they provide a user
interface that clashes with guidelines. You take the same risk with Windows Store apps.
Do as romans do (and don't reinvent the wheel)
The fifth principle of Windows Store applications is a tricky corollary of the fourth. It just strengthens
the importance of giving applications a user interface that fits well with the system's user interface.
Not only do you want to make apps consistent with the system, but you also want to achieve that by
using tools and templates offered by the Windows 8 stack of choice.
For this reason, you'll be using extensively the aforementioned WinJS library in the upcoming
chapters. WinJS is the repository of the native tools for building Windows Store applications with
HTML and JavaScript. You'll find an introduction to the library in the next section.
Collaborate (and don't reinvent the wheel)
Full integration with the host platform is a winning point of any Windows Store application, as it
allows users to feel at home with just about any application. Furthermore, it also enables distinct
applications to interact and exchange data.