TextBox - прокрутка мышкой

class MouseScrollableTextBox : TextBox
{
    protected override void WndProc(ref Message m)
    {
        switch (m.Msg)
        {
            case 0x020A: // WM_MOUSEWHEEL
                if (((int)m.WParam >> 16) > 0)
                    m.WParam = (IntPtr)0; // SB_LINEUP
                else
                    m.WParam = (IntPtr)1; // SB_LINEDOWN
                m.Msg = 277; // WM_VSCROLL;
                base.WndProc(ref m);
                break;

            default:
                base.WndProc(ref m);
                break;
        }
    }
}