DataGridViewWithBackgroundImage.csx

#r "System.Windows.Forms"
#r "System.Drawing"

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

Application.Run(new Form1());

public class Form1 : Form
{

    private DataGridViewEx dataGridView1 = new DataGridViewEx();
    DataGridViewComboBoxColumn comboBoxColumn;
    DataGridViewComboBoxColumn comboBoxDetailColumn;
    
    public Form1()
    {
        this.Load += FormLoad;
        this.Controls.Add(dataGridView1);
    }

    private void AddColorColumn()
    {
        comboBoxColumn = new DataGridViewComboBoxColumn();
        comboBoxColumn.Items.AddRange(
            Color.Red, Color.Yellow, Color.Green, Color.Blue);
        comboBoxColumn.ValueType = typeof(Color);
        dataGridView1.Columns.Add(comboBoxColumn);
        comboBoxDetailColumn = new DataGridViewComboBoxColumn();
        comboBoxDetailColumn.ValueType = typeof(Color);
        dataGridView1.Columns.Add(comboBoxDetailColumn);
    }
    
    private void FormLoad(object sender, EventArgs e)
    {
        AddColorColumn();
        dataGridView1.BackgroundImage = Image.FromFile(
            "C:\\Windows\\Web\\Screen\\img103.png");
        dataGridView1.SetCellsTransparent();
    }
}

public class DataGridViewEx : DataGridView
{
    private Image _backgroundPic;

    public override Image BackgroundImage
    {
        get { return _backgroundPic; }
        set { _backgroundPic = value; }
    }

    protected override void PaintBackground(System.Drawing.Graphics graphics,
        System.Drawing.Rectangle clipBounds, System.Drawing.Rectangle gridBounds)
    {
        base.PaintBackground(graphics, clipBounds, gridBounds);

        if (((this.BackgroundImage != null)))
        {
            graphics.FillRectangle(Brushes.Black, gridBounds);
            graphics.DrawImage(this.BackgroundImage, gridBounds);
        }
    }
    
    public void SetCellsTransparent()
    {
        this.EnableHeadersVisualStyles = false;

        this.ColumnHeadersDefaultCellStyle.BackColor = Color.Transparent;

        this.RowHeadersDefaultCellStyle.BackColor = Color.Transparent;

        foreach (DataGridViewColumn col in this.Columns)
        {
            col.DefaultCellStyle.BackColor = Color.Transparent;
        }
    }
}