Velocity integration: automatic data language detection using double file extension not working

In a blog post from 2009
http://blogs.jetbrains.com/idea/tag/template-data-languages/

it was mentioned that
"IntelliJ IDEA Velocity integration is also capable of determining the  language by a double file extension (e.g. foo.java.vm or bar.css.ft)"

However, that does not work for me.  I have files like something.properties.vtl, and intellij was able to detect that it was a velocity template, but would assume the underlying data language to be "plain text".  If I manually choose data language to be properties file then syntax highlighting etc works fine.   How do I make intellij automatically detect the data language in this case?   Do I need to edit some configuration setting?  I am running IU-10.5.2 on mac os x 10.6