No support for TLD-defined scripting variables?

I've created a custom tag which defines a scripting variable. The variable is defined in the TLD file with:

    test
    ...
    
        id
        SomeClass
    
]]>

In the JSP I use this code:

    <%= xyz.toString() %>
]]>

Everything works OK, but IDEA doesn't know anything about the variable 'xyz' and marks it in red.

If I use a TagExtraInfo class to define the scripting variable IDEA recogizes it.

Am I doing something wrong, is it a known bug or do I have to open a bug in the tracker?