C# DevExpress XtraMessageBox自定义字体，字体大小，自定义按钮大小，自定义Icon

    public static class UIMessageBox
    {
        static UIMessageBox()
        {
            MessageBoxForm.MessageBoxFont = new Font("Arial", 14F); //定义字体类型
        }

        static readonly Icon MessageBoxIcon = null;


        public static void Show(string message)
        {
            ShowInternal(null, message, "Notice", SystemIcons.Information, DialogResult.OK);
        }

        public static void Show(Control owner, string message)
        {
            ShowInternal(owner, message, "Notice", SystemIcons.Information, DialogResult.OK);
        }

        private static DialogResult ShowInternal(Control owner, string message, string caption, Icon messageIcon, params DialogResult[] dialogResults)
        {
            MessageBoxForm form = new MessageBoxForm();
            form.Icon = MessageBoxIcon;
            XtraMessageBoxArgs args = new XtraMessageBoxArgs(owner, message, caption, dialogResults, messageIcon, 0);
            args.Showing += Args_Showing;
            return form.ShowMessageBoxDialog(args);
        }

        private static void Args_Showing(object sender, XtraMessageShowingArgs e)
        {
            MessageButtonCollection buttons = e.Buttons as MessageButtonCollection;
            SimpleButton btn = null;
            foreach (var dialog in (DialogResult[])Enum.GetValues(typeof(DialogResult)))
            {
                btn = buttons[dialog] as SimpleButton;
                if (btn != null)
                {
                    btn.Size = new Size(Convert.ToInt32(btn.Width * 1.2), Convert.ToInt32(btn.Height * 1.2)); //按钮大小
                    btn.Font = e.Form.Font; //按钮字体
                }
            }
        }
    }

    internal class MessageBoxForm : XtraMessageBoxForm
    {
        internal static Font MessageBoxFont = new Font("Arial", 10F);

        public MessageBoxForm()
        {
            Appearance.Font = MessageBoxFont;
        }

        protected override FormPainter CreateFormBorderPainter()
        {
            return new MessageBoxFormPainter(this, LookAndFeel);
        }
    }

    internal class MessageBoxFormPainter : FormPainter
    {
        internal MessageBoxFormPainter(Control owner, ISkinProvider provider) : base(owner, provider) { }

        protected override void DrawText(GraphicsCache cache)
        {
            string text = Text;
            if (text == null || text.Length == 0 || TextBounds.IsEmpty)
                return;
            AppearanceObject appearance = new AppearanceObject(GetDefaultAppearance());
            appearance.Font = Owner.Font;
            appearance.TextOptions.Trimming = Trimming.EllipsisCharacter;
            Rectangle r = RectangleHelper.GetCenterBounds(TextBounds, new Size(TextBounds.Width, appearance.CalcDefaultTextSize(cache.Graphics).Height));
            DrawTextShadow(cache, appearance, r);
            cache.DrawString(text, appearance.Font, appearance.GetForeBrush(cache), r, appearance.GetStringFormat());
        }

        protected override int CalcTextHeight(Graphics graphics, AppearanceObject appearance)
        {
            return (int)(graphics.MeasureString(Text, Owner.Font).Height); //标题栏的高度
        }
    }

UIMessageBox.Show("This is a message");