Flex 4 Library Project -Type not found or not a compile-time constant: Matrix3D

I spent some time tonight upgrading the Flextras watermarking code to the Flex 4 SDK. I've done this before without problems, but the latest beta is giving me a bunch of errors, similar to these:

"Type not Found or not a compile-time constant: Matrix3D" "Type not Found or not a compile-time constant: Number" "Type not Found or not a compile-time constant: Vector"

After some Googling around I discovered that the fix is easy if you're using a simple Flex Project. My good friend Simeon had my back, this time without even knowing it. His blog post directed me to shortfusion blog which lets me know this is a type mismatch with player versions. I must specify that the player version for my project is Flash Player 10 or higher for this error to go away.

The shortfusion blog has a great screenshot showing you how to update the player version for your Flex Project. Unfortunately, that is where I hit a snag. That screen is not available for Flex Library Projects. What is the solution? You can use a command line compiler option on the specify the targeted player in a Library project. Just add this line to the compiler settings:

You can see the setting page here: