问Winforms:在UserControl中添加关闭"x“按钮

EN

using System;
using System.Drawing;
using System.Windows.Forms;
using System.Windows.Forms.VisualStyles;

class Form1 : Form
{
    [STAThread]
    static void Main()
    {
        //Application.EnableVisualStyles();
        Application.SetCompatibleTextRenderingDefault(false);
        Application.Run(new Form1());
    }

    public Form1()
    {
        SetStyle(ControlStyles.OptimizedDoubleBuffer | ControlStyles.UserPaint | ControlStyles.Opaque | ControlStyles.AllPaintingInWmPaint, true);
    }

    Rectangle buttonRect = new Rectangle(10, 10, 50, 20);
    ButtonState buttonState = ButtonState.Normal;

    protected override void OnMouseMove(MouseEventArgs e)
    {
        if (buttonRect.Contains(e.Location))
            buttonState = Capture ? ButtonState.Pushed : ButtonState.Checked;
        else
            buttonState = ButtonState.Normal;
        Invalidate(buttonRect);

        base.OnMouseMove(e);
    }

    protected override void OnMouseDown(MouseEventArgs e)
    {
        if (e.Button == MouseButtons.Left && buttonRect.Contains(e.Location))
        {
            Capture = true;
            buttonState = ButtonState.Pushed;
            Invalidate(buttonRect);
        }

        base.OnMouseDown(e);
    }

    protected override void OnMouseUp(MouseEventArgs e)
    {
        if (Capture)
        {
            Capture = false;
            Invalidate(buttonRect);
            if (buttonRect.Contains(e.Location))
            {
                // The button was clicked

                MessageBox.Show("You clicked the button.");
            }
        }

        base.OnMouseUp(e);
    }

    protected override void OnPaint(PaintEventArgs e)
    {
        e.Graphics.FillRectangle(SystemBrushes.Window, e.ClipRectangle);

        VisualStyleRenderer renderer = null;
        if (Application.RenderWithVisualStyles)
        {
            switch (buttonState)
            {
                case ButtonState.Checked:
                    if (VisualStyleRenderer.IsElementDefined(VisualStyleElement.Window.CloseButton.Hot))
                        renderer = new VisualStyleRenderer(VisualStyleElement.Window.CloseButton.Hot);
                    break;
                case ButtonState.Pushed:
                    if (VisualStyleRenderer.IsElementDefined(VisualStyleElement.Window.CloseButton.Pressed))
                        renderer = new VisualStyleRenderer(VisualStyleElement.Window.CloseButton.Pressed);
                    break;
                default:
                    if (VisualStyleRenderer.IsElementDefined(VisualStyleElement.Window.CloseButton.Normal))
                        renderer = new VisualStyleRenderer(VisualStyleElement.Window.CloseButton.Normal);
                    break;
            }
        }

        if (renderer != null)
            renderer.DrawBackground(e.Graphics, buttonRect);
        else
            ControlPaint.DrawCaptionButton(e.Graphics, buttonRect, CaptionButton.Close, buttonState);

        base.OnPaint(e);
    }
}