From FDT Documentation
Right now is an exciting time for Flash development. Soon there will be mobile AIR development, mobile Flex development and new Flash/Flex features continuously being added. This makes SDK management particularly important.
This tutorial will go over the basics of managing SDKs with FDT.
FDT & SDKs
FDT an IDE specializing in for creating applications for the desktop and web - whether your using the Flex framework, ActionScript only or even haXe. But in order to do this, it needs to know what tools to use in order to get you to where you want. That is where SDKs come in.
Think of your finial application as a piece of hand crafted furniture. In this scenario, you're the master craftsman and FDT is your right hand assistant.