Support for developing applications based on ActionScript and Flex is not bundled with IntelliJ IDEA. You can install the Flash/Flex plugin from the JetBrains repository as described in Install plugins.
You can find the documentation for ActionScript and Flex in earlier versions of IntelliJ IDEA Help.
Related blog posts:
The Extract Interface and Extract Superclass refactorings for Flex and ActionScript
The Change Method Signature refactoring for ActionScript and Flex
New in IntelliJ IDEA 10.5: Develop Mobile AIR Applications for Android
Last modified: 21 April 2023