While primarily a consideration for mobile and modern portable devices, an application layout should be designed with the physical design of the device in mind. Visual and interaction technologies on the desktop have remained largely consistent for 25 years, leading to standardized interface designs—but this too is changing. Computers are now more commonly shipping with ultra high definition screens, many of which are also touch surfaces. If your approach to cross-platform application development is to also include mobile devices, you will need to consider the small screen sizes as well as orientation of the device.

Of course, the screen isn't the only factor to consider; it's now also common for input devices to vary. A mouse and keyboard is probably the main configuration for user input but many portable computers now have a tablet mode where touch input is a replacement for the mouse and a virtual keyboard can appear for text input. If this is a configuration you want to support, then your layout will need to work when parts of the screen (probably the bottom edge) is covered with the virtual keyboard. More importantly, finger-based input (most commonly called multi-touch) is far richer than a point and click approach; will your application aim to support pinch to zoom or touch rotation? If you intend to support these sorts of features, then make sure your chosen framework supports input gestures. Each toolkit is evolving rapidly and so the details have been omitted from this book as it would be out of date by publication.

In addition to the full device capabilities, a traditional desktop application can be moved around and made different sizes or orientations by many user actions—should your design aim to accommodate these changes in configuration? When displaying applications side by side on a tablet device, you'll see how powerful the different layouts can be when implemented correctly.