Read original post at Marco Minerva's Blog
The Flyout XAML Control that ships with Windows 8.1 lacks a Dependency Property, let’s say IsOpen, that allows to control it using the MVVM pattern. Actually, opening it is not a problem, because it is tipically associated to a Button control, and so it is automatically shown when we tap on it. The problem arises when we need to close the flyout, for example when we click a command button. The only way to programmatically close the popup is to call its Hide method.
If we’are following the MVVM pattern, however, we should have on the Flyout a property that we can change to show and hide it: this property must be bounded to the View Model.