C#

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        public static string[] Names = new string[] {"Jon Smith", "Fred Perry", "Foo Bar" };
        public static string[] Sentences = new string[] { "Hi hello!", "Bye", "Peace and long life", "Live long and prosper" };

        Props properties = new Props();

        public Form1()
        {
            InitializeComponent();

            propertyGrid1.SelectedObject = properties;
        }

        private void button1_Click(object sender, EventArgs e)
        {
            properties.SwopList();
            propertyGrid1.Refresh();
        }
    }

    public class Props
    {
        string name = Form1.Names[0];
        string sentence = Form1.Sentences[0];
        string item;

        public Props()
        {
            item = name;
        }

        public void SwopList()
        {
            PropertyDescriptorCollection pdc = System.ComponentModel.TypeDescriptor.GetProperties(this);
            PropertyDescriptor pd = pdc["Item"];

            if (pd.Converter is NameList)
            {
                item = sentence;
                //pd.Converter = typeof(SentenceList);  // Don't work
            }
            else if (pd.Converter is SentenceList)
            {
                item = name;
                //pd.Converter = typeof(NameList);  // Don't work
            }
        }

        [TypeConverter(typeof(NameList))]
        public string Item
        {
            get { return item; }
            set { item = value; }
        }
    }

    public class NameList : TypeConverter
    {
        public override bool GetStandardValuesSupported(ITypeDescriptorContext context)
        {
            return true;
        }

        public override StandardValuesCollection GetStandardValues(ITypeDescriptorContext context)
        {
            return new StandardValuesCollection(Form1.Names);
        }
    }

    public class SentenceList : TypeConverter
    {
        public override bool GetStandardValuesSupported(ITypeDescriptorContext context)
        {
            return true;    // Display Drop-down menu
        }

        public override StandardValuesCollection GetStandardValues(ITypeDescriptorContext context)
        {
            return new StandardValuesCollection(Form1.Sentences);
        }
    }
}