use GetFlyouts() helper method instead of Flyouts.Items for MVVM scenario's
Merge pull request #1008 from remcoros/master

use GetFlyouts() helper method instead of Flyouts.Items for MVVM scenariios
Fix missing flyout external click code

How did I forget that piece of code and named a MouseDown event handler KeyDown!?
Merge pull request #1011 from 100GPing100/patch-6

Fix missing flyout external click code
Fix window commands focus visual style
Merge pull request #1012 from 100GPing100/patch-7

Fix window commands focus visual style