System.Windows.Forms.ColorPickerForm.AlphaPicker.OnMouseMove C# (CSharp) Méthode

            protected override void OnMouseMove(MouseEventArgs e)
            {
                if (_mouseDown)
                {
                    Alpha = (float)e.X / Width;
                    if (Alpha < 0) Alpha = 0;
                    if (Alpha > 1) Alpha = 1;
                }
            }
            protected override void OnMouseUp(MouseEventArgs e)