In commit 38757 the 'getDivClass' method was removed in favour of a 'getDivID' method:

http://svn.magnolia-cms.com/view/community/modules/standard-templating-kit/trunk/magnolia-module-standard-templating-kit/src/main/java/info/magnolia/module/templatingkit/templates/MainAreaIntro.java?r1=32669&r2=38757

Unfortunately our own mainAreaIntro ftl uses this functionality, and we do need different classes for this div in different sites.

I would suggest re-adding this method with the old functionality, and keeping the getDivID method as well.