In the class info.magnolia.module.templatingkit.style.BodyClassResolver.java the allowed body classes are defined:
private static String[] allowedBodyClasses =

{ "col", "nav-col", "col-subcol", "col-subcol-equal", "col-float3", "col-float2", "nav-col-float2", "col-float2-subcol", "col-subcol-subcol" }

;

If anything is configured by the user which is out of this definitions, a, error is generated in the log:
ERROR nolia.module.templatingkit.style.BodyClassResolver: Is not an allowed body class: nav-col-subcol-subcol

This can be very easily achieved by changing the extrasArea.columns=2 (two extras areas).
This means in consequences, that the used can configure within a site-definition a set which:

• This error is produced
• No body class shows on the page
  And the only way to solve this is by subclassing the BodyClassResolver class.

I think it makes no sense, to provide by configuration possibilities which finally drag a need to subclass.
That's why i want to raise here the questions, whether the 'allowedBodyClasses' shouldn't be configurable somwhere (site-def or so)?
And if not the variable should at least be protected for subclassing it better.