This technique uses bitmaps and hit regions to create a GUI component. WinAmp is a good example of using this technique. However bitmaps don't scale well, so if your GUI needs to resize you usually have to define bitmaps for each of the sizes you want to support. Vector Graphics - Vector graphic components are just as easy for a graphic artist to create as bitmap graphics. With the right tools, it is trivial to convert vector graphics into a form that is directly usable in your application.
Vector graphics have several advantages.
They are easy to paint, they are easy to turn into regions, they are easy to hit-test, and they translate, rotate and scale easily. Hopefully you will see how trivial vector graphics are to used in applications. This technique allows GUI components to be rendered on the fly. This means there is a definition for the components of the image that are rendered using an rendering engine such as DirectX or OpenGl. This technique is applied currently to games.