void Footer_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
{
//get the mouse's current position inside of the Window
start = e.GetPosition(Application.Current.MainWindow);
//get the current size of the element
OriginalWidthandHeight.X = this.ThisControlGrid.ActualWidth;
OriginalWidthandHeight.Y = this.ThisControlGrid.ActualHeight;
//capture the mouse on the element to indicate that it is in use
Footer.CaptureMouse();
}