Designing Lookless Controls in Windows Presentation Foundation

hen Microsoft set about building the Windows Presentation Foundation, one core goal was to create an environment for applications capable of both two-dimensional and three-dimensional content simultaneously. Using a traditional approach, this would have led to an abstract Button class followed by Button2D and Button3D subclasses that would override the painting rules. Tearing a page from the CSS-based Internet, Microsoft also wanted the look and feel of all controls to be controllable via styles that, when updated, would in turn update the look and feel of every component of that type in the application.

Microsoft's solution is called "Lookless" controls. A Lookless control is a control that defines the behavior of a control without regard to how it will look when rendered. For example, a button is a control that has a normal state, a mouseover state and a clicked state. The appearance of the button could be anything—from the familiar grey box to an obnoxiously spinning 3D flaming corporate logo circa web design 1997 style.