Why this isn’t set up to work by default for Actionscript Projects is beyond me, but I found a need to use the fl.color Class this week in Flash and it sure was a challenge to get the fl.* libraries to work natively within Flex Builder 3 for Mac.
Here is how you do it:
1. Right click on your project folder in Flex, click “Properties.”
2. Click on the “Actionscript Build Path” menu item.
3. Click “Add Folder”
4. Navigate to: /Applications/Adobe Flash/Common/Configuration/Actionscript 3.0/projects/Flash/src/
5. Click “Choose” to select the /src/ folder and “Ok” to add this to your source path.
You can do the same thing for Windows based Flex Builder as well, the file path should be similar to this:
C:\Program Files\Adobe\Adobe Flash CS3\en\Configuration\ActionScript 3.0\Classes
P.S. Speaking of fl.color, fl.color.setTint() is a great trick to tinting without having to deal with the more complex colorTransform class.