public class CalendarGcComboBoxCellType : CalendarInputManCellBaseType 

using System;
using System.Windows.Forms;
using System.Drawing;
using GrapeCity.Win.CalendarGrid.InputMan;
using GrapeCity.Win.CalendarGrid;

namespace CalendarGridSampleCode
{
    class GcComboBoxCellDemo : Form
    {
        private GcCalendarGrid gcCalendarGrid1 = new GcCalendarGrid();
        private Label label = new Label();

        public GcComboBoxCellDemo()
        {
            this.Text = "GcComboBoxCell Demo";
            this.Size = new Size(350, 300);

            // Add GcCalendarGrid to form
            this.gcCalendarGrid1.Dock = DockStyle.Fill;
            this.Controls.Add(this.gcCalendarGrid1);

            this.label.Dock = DockStyle.Bottom;
            this.label.Height = 50;
            this.label.BackColor = SystemColors.Info;
            this.label.Text = "You can select one item from the DropDownList; hit the F4 to show the DropDownList.";
            this.Controls.Add(label);

            this.Load += Form1_Load;

            this.StartPosition = FormStartPosition.CenterScreen;
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            CalendarGcComboBoxCellType gcComboBoxCell1 = new CalendarGcComboBoxCellType();
            gcComboBoxCell1.DropDownStyle = CalendarGridComboBoxStyle.DropDown;

            gcComboBoxCell1.Items.AddRange(new string[] { "One", "Two", "Three" });

            CalendarTemplate template1 = CalendarTemplate.CreateDefaultTemplate();
            template1.Content[1, 0].CellType = gcComboBoxCell1;
            template1.Content[2, 0].CellType = gcComboBoxCell1.Clone();

            gcCalendarGrid1.Template = template1;
        }

        [STAThreadAttribute()]
        public static void Main()
        {
            Application.EnableVisualStyles();
            Application.Run(new GcComboBoxCellDemo());
        }
    }
}