Cannot force IDEA to work with maven created Flex project

I am using IDEA 10.5.4 (I have licence for that version of IDEA)

I have maven project which part are Flex mxml files.

Application compiles with maven and works properly when target war is deployed in tomcat.

Maven project has dependency to Flex 3.5 version.

I have run mvn idea:idea in project directory.

After that I have imported created ipr file to IDEA.

All source files are visible in project view, but IDEA seems to do not recognize Flex code.

Even after I have made Add Framework Support for project and pointed to extracted Flex 3.6a SDK  in source code IDEA is pointing to errors in <mx:Script> like: Unresolved type String or Unresolved type Boolean.

How to force IDEA to recognize Flex syntax?