MahApps/MahApps.Metro — pull request #1638 by jonferreira (2014-11-06 16:46:54+00:00)
Title: Update FlyoutsControl.cs

i'm using a `````` binded to an ```ObservableCollection``` but when i remove items from Flyout Collection i get a Value can't be null error.

Following the recent conversation with thoemmi in Gitter i changed FlyoutControl to check for null before advancing