Recently used files—Command, MultiItem, and ComboBox
RecentFilesRegistryHelper.cs
// Copyright 2010 ESRI
// 
// All rights reserved under the copyright laws of the United States
// and applicable international laws, treaties, and conventions.
// 
// You may freely redistribute and use this sample code, with or
// without modification, provided you include the original copyright
// notice and use restrictions.
// 
// See the use restrictions.
// 

using System;
using System.Collections.Generic;
using System.Text;
using ESRI.ArcGIS.Framework;
using Microsoft.Win32;

namespace RecentFilesCommandsCS
{
    /// <summary>
    /// Helper class to process recent file lists stored in the registry
    /// </summary>
    class RecentFilesRegistryHelper
    {
        const string RecentFileRegistryKeyPath = @"Software\ESRI\{0}\Recent File List";
        public static string[] GetRecentFiles(IApplication app)
        {
            List<string> recentFilePaths = new List<string>();

            //Read the registry to get the recent file list
            string openKey = string.Format(RecentFileRegistryKeyPath, app.Name);
            RegistryKey recentListKey = Registry.CurrentUser.OpenSubKey(openKey);
            if (recentListKey != null)
            {
                string[] listNames = recentListKey.GetValueNames();
                foreach (string name in listNames)
                {
                    string fileName = recentListKey.GetValue(name, string.Empty).ToString();
                    if (!string.IsNullOrEmpty(fileName))
                        recentFilePaths.Add(fileName);
                }
            }

            return recentFilePaths.ToArray();
        }
    }
}