如何使用c#加宽winforms滚动条

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

public class CustomScrollBar : ScrollBar
{
    private int scrollBarWidth = 20; // 自定义滚动条的宽度

    public int ScrollBarWidth
    {
        get { return scrollBarWidth; }
        set { scrollBarWidth = value; }
    }

    protected override void OnPaint(PaintEventArgs e)
    {
        base.OnPaint(e);

        // 绘制滚动条的背景
        e.Graphics.FillRectangle(Brushes.Gray, ClientRectangle);

        // 绘制滑块
        Rectangle thumbRect = new Rectangle(0, 0, scrollBarWidth, Height);
        e.Graphics.FillRectangle(Brushes.DarkGray, thumbRect);

        // 绘制箭头
        Rectangle arrowRect = new Rectangle(0, 0, scrollBarWidth, scrollBarWidth);
        e.Graphics.FillPolygon(Brushes.White, new Point[]
        {
            new Point(scrollBarWidth / 2, scrollBarWidth / 4),
            new Point(scrollBarWidth / 4, scrollBarWidth / 2),
            new Point(scrollBarWidth * 3 / 4, scrollBarWidth / 2)
        });
    }
}

public partial class MainForm : Form
{
    private CustomScrollBar customScrollBar;

    public MainForm()
    {
        InitializeComponent();

        customScrollBar = new CustomScrollBar();
        customScrollBar.ScrollBarWidth = 30; // 设置滚动条的宽度
        customScrollBar.Dock = DockStyle.Right;

        // 将自定义滚动条控件添加到窗体中
        Controls.Add(customScrollBar);
    }
}