Textbox禁止剪切，复制，粘贴和弹出右键菜单

以下代码可以禁止TextBox 剪切，复制，粘贴和弹出右键菜单

protected override void WndProc(ref Message m)
{
    /* Deny cut, copy and paste */
    if (m.Msg == 0x0301) /* WM_COPY */
    {
        return;
    }

    if (m.Msg == 0x0300) /* WM_CUT */
    {
        return;
    }

    if (m.Msg == 0x0302) /* WM_PASTE */
    {
        return;
    }

    /* Remove the context menu (after all we can't cut/copy/paste, so it's not much good to us anyway!) */
    if (m.Msg == 0x007B) /* WM_CONTEXTMENU */
    {
        return;
    }

    base.WndProc(ref m);
}