"By now, every developer, in some way, has experienced the productivity enhancements that the modern rapid application development environment offers. Developers use these environments to build different applications for different reasons. Some applications are structured only for the internal use of business. Some applications are sold commercially. Yet other applications are developed and freely distributed by hobbyists that enjoy contributing to the software community. No matter what the intent, the basic building blocks of each application's user interface are the elemental pieces referred to as controls. ... When a developer uses Microsoft Visual Studio .NET 2003 to create custom controls for smart device applications the process is tedious and error-prone. Creating a custom control that functions solely at run time almost seems trivial. Unfortunately, getting that custom control to properly integrate with the designer can be frustrating for Visual C# developers, and it is not possible for Visual Basic developers. But that was then; now, Visual Studio 2005 has changed the way that developers build design-time support for custom controls."
Do want to learn how to create custom controls for your mobile applications? Then this article might help you out.