.net自定义MessageBox文本高亮显示

为什么？

我在C#中构建了一个简单的自定义MessageBox作为对话框。当我通过show（）显示消息框时，消息文本不会高亮显示。当我显示此消息框vi ShowDialog（）时，文本将突出显示。

我不希望我的文本被突出显示。有什么想法吗？

public partial class MyMessageBox : Form
    {
        private String mCaption;
        private String mMessage;

        public MyMessageBox( Form anOwner, String aCaption, String aMessage )
        {
            InitializeComponent();
            mCaption = aCaption;
            Owner = anOwner;
            mMessage = aMessage;
        }

        private void btnCancelRequest_Click( object sender, EventArgs e )
        {
            ( (AddressForm)Owner ).RequestCancelled();
        }

        private void btnOk_Click( object sender, EventArgs e )
        {
            CloseDialog();
        }

        public void CloseDialog()
        {
            Close();
        }

        // Called from the Address Form
        public void HideCancelRequestButton()
        {
            btnCancelRequest.Visible = false;
        }

        private void MyMessageBox_Activated( object sender, EventArgs e )
        {
            Text = mCaption;
            txtMessage.Text = mMessage;
        }
    }

txtMessage.SelectionLength = 0;