I followed the great example at:

http://www.richardsoeteman.net/2010/01/04/CreateACustomMacroParameterType.aspx

for creating a custom macro parameter of type DropDownList. Few hiccups, but ultimately worked great. I tried creating a custom macro parameter of type CheckBoxList, however, and can't get it to work. I don't think it's in my code, per se, but something about the way it interacts with umbraco. The control shows up as a valid parameter type in the macro, and when I insert the macro into a template, it prompts with the 2 values, but clicking OK to insert the macro into the template does nothing and returns the javascript error:

Error: document.forms[0][controlId] is undefined

My code below

Any assistance appreciated,

Jonathan

using System;
using System.Web.UI.WebControls;
using umbraco.interfaces;
using System.Collections.Generic;

namespace CRD.umbraco
{
    public class PickLeftAndOrRight : CheckBoxList, IMacroGuiRendering
    {
        protected override void OnLoad(EventArgs e)
        {
            base.OnLoad(e);

            if (this.Items.Count == 0)
            {
                this.Items.Add(new ListItem("Left", "left"));
                this.Items.Add(new ListItem("Right", "right"));
            }
        }

        #region IMacroGuiRendering Members

        public bool ShowCaption
        {
            get { return true; }
        }

        public string Value
        {
            get
            {
                // also tried explicitly getting value a la:
                // return "left";
                // and commenting out the rest

                List<string> selectedItems = new List<string>();
                foreach (ListItem item in this.Items)
                {
                    if (item.Selected)
                        selectedItems.Add(item.Value);
                }
                return string.Join(",", selectedItems.ToArray());
            }
            set
            {
                // also tried explicitly setting value a la:
                // this.Items[0].Selected = true;
                // and commenting out the rest

                List<string> selectedItems = new List<string>(value.Split(new char[] { ',' }));

                foreach (ListItem item in this.Items)
                {
                    if (selectedItems.Contains(item.Value))
                        item.Selected = true;
                }
            }
        }

        #endregion
    }
}