the locate*() methods are static, so it doesn't matter. there are other
methods in KStandardDirs that aren't static (and so require an object) and for
those ones, KGlobal::dirs() is the way to go.

you find this:

http://api.kde.org/4.x-api/kdelibs-apidocs/kdecore/html/namespaceKGlobal.html

nicely hidden. :/