Mine

public void Update( float deltaTime )
        {
            if( Hidden )
                return;

            MouseDelta = Game.InputManager.MousePositionInGame - MousePreviousPosition;

            if
                (
                IsDraggableFrom( Game.InputManager.MouseDownFromInGame ) &&
                IsDraggableFrom( Game.InputManager.MousePositionInGame ) &&
                Game.InputManager.MouseDown &&
                Game.InputManager.MouseButtons == System.Windows.Forms.MouseButtons.Left
                )
                IsDragging = true;

            for( int i = 0; i < Game.WindowManager.WindowPool.Count; i++ )
            {
                if( i == Game.WindowManager.GetWindowIndex( this ) )
                    continue;

                if( Game.WindowManager.WindowPool[ i ].IsDragging )
                    IsDragging = false;
            }

            if( IsDragging )
            {
                Game.WindowManager.MoveToFront( Game.WindowManager.GetWindowIndex( this ) );
                Position += MouseDelta;
            }

            if( !Game.InputManager.MouseDown )
                IsDragging = false;

            if
                (
                IsSelectable( Game.InputManager.MouseDownFromInGame ) &&
                IsSelectable( Game.InputManager.MousePositionInGame ) &&
                !IsDragging &&
                !Hidden &&
                Game.InputManager.MouseDown
                )
            {
                bool MoveToFront = true;

                for( int i = 0; i < Game.WindowManager.WindowPool.Count; i++ )
                {
                    if( Game.WindowManager.WindowPool[ i ].IsDragging )
                        MoveToFront = false;
                }

                if( MoveToFront )
                    Game.WindowManager.MoveToFront( this );
            }

            MousePreviousPosition = Game.InputManager.MousePositionInGame;
        }