In previous Windows development frameworks, custom controls played a central role. But in WPF, the emphasis has shifted. Custom controls are still a useful way to build custom widgets that you can share between applications, but they’re no longer a requirement when you want to enhance and customize core controls. (To understand how remarkable this change is, it helps to point out that this book’s predecessor, Pro .NET 2.0 Windows Forms and Custom Controls in C#, had nine complete chapters about custom controls and additional examples in other chapters. But in this book, you’ve made it to Chapter 18 without a single custom control sighting!)