1.2. It's a Windowing Toolkit

Flex 2 adds a powerful, extensible, well-organized, and well-documented windowing toolkit to the capabilities of Flash Player 9. Much of the value of Flex 2 is in the framework: the hundreds of classes that you have at your disposal to use and extend.

Most of these classes address both the layout and display of familiar GUI components such as buttons, text input fields, and toolbars. Like any windowing toolkit, its duty is to keep you from ever writing another scrollbar (or insert name of another UI class you are tired of rewriting). You can entrust Flex with all sorts of middling details—centering objects, replacing the user's mouse cursor, or populating list boxes with data—and get straight to the important part of your application.