key for FlatButton style (MetroFlatButton)
Changes to the "checked animation"

XAML generated an error if not already compiled

same problem as this:

http://stackoverflow.com/questions/13168740/unknown-property-does-not-point-to-a-dependencyobject-in-path-0-13-2/15106546#15106546
fix keyboard focus for flyouts
Merge branch 'master' of https://github.com/MahApps/MahApps.Metro

Conflicts:
	FlyoutDemo/MainWindow.xaml