Let’s master the Flex Controls
The first obvious step would be to look at the source code implementation located at <Flex 3.1.0 SDK Installation Directory\frameworks\projects\framework\src\mx\core\UIComponent.as>
In my opinion the most effective approach for creating your own custom controls is to extend them from the base controls and customize by overriding and digging into the source code of the base controls.
Some of the common methods, that you might want to override in your custom component are
Refer to the next post for creating the custom flex UIComponent