Creating Custom MXML Components
An application in Adobe Flex typically consists of an MXML application file (a file with an <mx:Application> parent tag), one or more standard Flex components, and one or more custom components defined in separate MXML, ActionScript, or Flash component (SWC) files. By dividing the application into manageable chunks, you can write and test each component independently from the others. You can also reuse a component in the same application or in other applications, which increases efficiency.
You can use Adobe Flex Builder to build custom MXML and ActionScript components visually and then insert them into your applications. This topic describes how to build custom MXML components visually. For more information on building ActionScript components, see Creating an ActionScript class.
You can also build an MXML component directly using code. For more information, see Simple MXML Components in Creating and Extending Adobe Flex 3 Components.