private bool IsShiftDown(System.Windows.Input.KeyboardDevice keyboard)
 {
     return keyboard.IsKeyDown(System.Windows.Input.Key.LeftShift) || keyboard.IsKeyDown(System.Windows.Input.Key.RightShift);
 }
 private bool IsControlDown(System.Windows.Input.KeyboardDevice keyboard)
 {
     return keyboard.IsKeyDown(System.Windows.Input.Key.LeftCtrl) || keyboard.IsKeyDown(System.Windows.Input.Key.RightCtrl);
 }