MahApps/MahApps.Metro — pull request #1164 by xxMUROxx (2014-03-17 08:25:15+00:00)
Title: ItemSource Should be IEnumerable and not ObservableCollection.

Explanation 1: If ItemSource is ObservableCollection I cannot bind a CollectionViewSource to it.
Explanation 2: Every control has an ItemsSource of IEnumerable

Related to #1158