在 WinForms 中ComboBox下拉框显示多列信息，请使用自定义控件：您可以创建一个自定义的下拉框控件，例如使用 DataGridView 控件作为下拉框的弹出列表，然后通过绘制和处理事件来使其表现为下拉框的样式。请进行代码检查并测试!

当然，我可以为您提供一个使用自定义控件的示例代码来实现多列下拉框的功能。以下是一个基于 DataGridView 的自定义下拉框控件的示例：

首先，创建一个名为 MultiColumnComboBox 的自定义控件类，继承自 ComboBox：

using System;
using System.Collections.Generic;
using System.Drawing;
using System.Windows.Forms;

public class MultiColumnComboBox : ComboBox
{
    private DataGridView dataGridView; // 用于显示下拉列表的 DataGridView 控件
    private bool isDroppedDown; // 标识下拉列表是否已展开

    public MultiColumnComboBox()
    {
        InitializeDataGridView();
        this.DropDown += MultiColumnComboBox_DropDown;
        this.DropDownClosed += MultiColumnComboBox_DropDownClosed;
        this.LostFocus += MultiColumnComboBox_LostFocus;
    }

    private void InitializeDataGridView()
    {
        dataGridView = new DataGridView();
        dataGridView.AutoGenerateColumns = false;
        dataGridView.AllowUserToAddRows = false;
        dataGridView.AllowUserToDeleteRows = false;
        dataGridView.RowHeadersVisible = false;
        dataGridView.SelectionMode = DataGridViewSelectionMode.FullRowSelect;

        // 添加列
        dataGridView.Columns.Add("Column1", "Column 1");
        dataGridView.Columns.Add("Column2", "Column 2");

        // 设置列宽度
        dataGridView.Columns[0].Width = 100;
        dataGridView.Columns[1].Width = 100;

        // 将 DataGridView 控件添加到 ComboBox 的 Controls 集合中
        this.Controls.Add(dataGridView);
    }

    private void MultiColumnComboBox_DropDown(object sender, EventArgs e)
    {
        if (this.Items.Count > 0 && !isDroppedDown)
        {
            int comboBoxHeight = this.Height;
            int comboBoxWidth = this.Width;

            // 设置下拉列表的位置和尺寸
            dataGridView.Location = new Point(this.Location.X, this.Location.Y + comboBoxHeight);
            dataGridView.Size = new Size(comboBoxWidth, this.PreferredHeight * 5);

            dataGridView.DataSource = GetDataSource(); // 将数据源绑定到 DataGridView

            dataGridView.CellClick += DataGridView_CellClick;
            dataGridView.KeyDown += DataGridView_KeyDown;

            isDroppedDown = true;

            dataGridView.Focus();
        }
    }

    private void MultiColumnComboBox_DropDownClosed(object sender, EventArgs e)
    {
        if (isDroppedDown)
        {
            dataGridView.CellClick -= DataGridView_CellClick;
            dataGridView.KeyDown -= DataGridView_KeyDown;

            isDroppedDown = false;

            this.Focus();
        }
    }

    private void MultiColumnComboBox_LostFocus(object sender, EventArgs e)
    {
        if (isDroppedDown)
        {
            dataGridView.CellClick -= DataGridView_CellClick;
            dataGridView.KeyDown -= DataGridView_KeyDown;

            isDroppedDown = false;
        }
    }

    private void DataGridView_CellClick(object sender, DataGridViewCellEventArgs e)
    {
        if (e.RowIndex >= 0 && e.RowIndex < dataGridView.Rows.Count && e.ColumnIndex >= 0 && e.ColumnIndex < dataGridView.Columns.Count)
        {
            this.SelectedItem = dataGridView.Rows[e.RowIndex].Cells[e.ColumnIndex].Value;
            this.Text = this.SelectedItem.ToString();

            this.DroppedDown = false;
        }
    }

    private void DataGridView_KeyDown(object sender, KeyEventArgs e)
    {
        if (e.KeyCode == Keys.Enter)
        {
            if (dataGridView.SelectedCells.Count > 0)
            {
                int rowIndex = dataGridView.SelectedCells[0].RowIndex;
                int columnIndex = dataGridView.SelectedCells[0].ColumnIndex;

                this.SelectedItem = dataGridView.Rows[rowIndex].Cells[columnIndex].Value;
                this.Text = this.SelectedItem.ToString();

                this.DroppedDown = false;
            }
        }
    }

    private object GetDataSource()
    {
        List<object[]> dataSource = new List<object[]>();

        // 添加数据到数据源
        dataSource.Add(new object[] { "Item 1 Column 1", "Item 1 Column 2" });
        dataSource.Add(new object[] { "Item 2 Column 1", "Item 2 Column 2" });
        dataSource.Add(new object[] { "Item 3 Column 1", "Item 3 Column 2" });

        return dataSource;
    }
}

然后，在您的 WinForms 窗体中使用这个自定义控件：

private void Form1_Load(object sender, EventArgs e)
{
    // 创建自定义的 MultiColumnComboBox 控件
    MultiColumnComboBox multiColumnComboBox = new MultiColumnComboBox();
    multiColumnComboBox.Location = new Point(50, 50);
    multiColumnComboBox.Size = new Size(200, 30);

    // 将自定义控件添加到窗体中
    this.Controls.Add(multiColumnComboBox);
}

这样，您就可以在 WinForms 窗体中使用自定义的 MultiColumnComboBox 控件，它可以显示多列的下拉列表项。请根据您的需求修改和调整代码。希望对您有所帮助！