Boolean bPaint = false;
        private void MenuItemMouseEnter(object sender, EventArgs e)
        {
            ToolStripMenuItem menuItem = sender as ToolStripMenuItem;

            if (menuItem != null)
            {
                bPaint = true;
                menuItem.Invalidate();
            }
        }

        private void MenuItemMouseLeave(object sender, EventArgs e)
        {
            bPaint = false; 
        }

        private void MenuItemPaint(object sender, PaintEventArgs e)
        {
            ToolStripMenuItem menuItem = sender as ToolStripMenuItem;

            if (menuItem != null)
            {
                if (bPaint)
                {
                    e.Graphics.FillRectangle(Brushes.Red, 0, 0, menuItem.Width, menuItem.Height);
                    Brush brush = new SolidBrush(Color.Black);
                    Font font = new Font(menuItem.Font.Name, menuItem.Font.Size);
                    e.Graphics.DrawString(menuItem.Text, menuItem.Font, brush, 20, 2);
                }
            }
        }

------解决方案--------------------
用WPF吧，哥们。

------解决方案--------------------
用其他控件
Dev，ComponmentOne 等