A Floating UWP ContentControl.
A XAML Control for the Universal Platform that can be dragged around the screen. Its position can optionally be restrained to a parent control’s rectangle or to the window itself. The control is decorated with an icon to indicate its ‘draggability’ behavior to the user.
Read the whole story here: https://xamlbrewer.wordpress.com/2016/02/08/a-floating-panel-control-for-uwp/.