MahApps/MahApps.Metro — pull request #991 by flagbug (2014-01-30 22:33:05+00:00)
Title: Simplify the WindowCommands handling for the clean window style

We introduce the property "OverrideDefaultWindowCommandsBrush" that is
default by null.
CleanWindowStyle ovverides this to "BlackBrush"

This fixes #990