Main-Klasse
-----------
        // OLD_FILES, reicht aus
        private void MainFile_Click(object sender, EventArgs e)
        {            
            SingVar instance = SingVar.getInstance();
            SingVar.callBack_checkFileopen delgt = checkFileopen;
            instance.createOldFilesMenuItems(MainFile, delgt);
        }

        // wenn Alt D gedrueckt wird
        private void MainFile_DropDownOpened(object sender, EventArgs e)
        {
            MainFile_Click(sender, e);
        }


        public void checkFileopen(string sFilename)
        {
            bool bIsOpen = false;
            foreach (Form childForm in MdiChildren)
            {
                string s = ((ChildForm)childForm).Filename;
                if (sFilename.Equals(((ChildForm)childForm).Filename, StringComparison.OrdinalIgnoreCase))
                {
                    childForm.Activate();
                    bIsOpen = true;
                    break;
                }
            }
            if (!bIsOpen)
            {
                OpenFile(sFilename);
                SingVar instance = SingVar.getInstance();
                instance.deleteFile(sFilename);
            }
        }




Utility-Klasse
--------------
public static string C_REG_ADR = "SOFTWARE\\WILHELM\\HTML";

        public delegate void callBack_checkFileopen(string sFilename);

        public void createOldFilesMenuItems(ToolStripMenuItem MainFile, callBack_checkFileopen delgt)
        {
            this.delgt = delgt;
            createList_OldFiles(MainFile);
            int n = oldfiles.Count;
            for (int i = 0; i < n; i++)
            {
                string sFile = (string) oldfiles[i];
                string sItem = "";
                switch (i+1) {
                    case 1:
                    case 2:
                    case 3:
                    case 4:
                    case 5:
                    case 6:
                    case 7:
                    case 8:
                    case 9:
                            sItem = "&" + (i + 1).ToString() + " " + sFile;
                            break;
                    case 10: sItem = "1&0 " + sFile;
                            break;
                    default: sItem = (i + 1).ToString() + " " + sFile;
                            break;
                }
                MyToolStripMenuItem mnItem = new MyToolStripMenuItem(sItem, sFile);
                mnItem.Name = "File" + (i + 1).ToString();
                mnItem.Size = new System.Drawing.Size(279, 22);
                mnItem.Tag = SingVar.C_OLDFILE_MARKER;
                MainFile.DropDownItems.Add(mnItem);
                mnItem.Click += new System.EventHandler(MnOldFile_Click);
            }
            saveOldFiles2Registry();
        }


         private void MnOldFile_Click(object sender, EventArgs e)
        {
            MyToolStripMenuItem mnItem = (MyToolStripMenuItem)sender;
            delgt(  mnItem.Filename );
            // checkFileopen((string)mnItem.Text);
            // MessageBox.Show((string)mnItem.Text);
        }


        public static void createList_OldFiles(ToolStripMenuItem MainFile)
        {
            // ToolStripMenuItem menu;
            // var eintrag1 = contextMenuStrip1.Items.Cast<ToolStripItem>().Where(m => m.Text == "Eintrag 1").FirstOrDefault();
            ToolStripItemCollection coll = MainFile.DropDownItems;
            // ToolStripSeparator
            int i = 0;
            ArrayList liste = new ArrayList();
            foreach (ToolStripItem control in coll)
            {
                if (control.GetType().Name.Equals("MyToolStripMenuItem"))
                {
                    liste.Add(i);
                    //menu = (ToolStripMenuItem)control;
                    //if ( (menu.Tag != null) )
                    //{                        
                    //    if ( ((string)menu.Tag).Equals(C_OLDFILE_MARKER) ) {
                    //        // MessageBox.Show(menu.Text, i + "");
                    //        liste.Add(i);
                    //    }
                    //}
                }
                i++;
            }
            for (i = liste.Count - 1; i >= 0; i--)
            {
                int j = (int)liste[i];
                coll.RemoveAt((int)liste[i]);
            }
        }


        // OLD_FILES  END


Zuaetzliche Klasse
------------------

 class MyToolStripMenuItem : ToolStripMenuItem
    {
        private string sFilename="";

        public string Filename
        {
            get { return sFilename; }
        }

        public MyToolStripMenuItem(string item, string sFilename)
            : base(item)
        {
            this.sFilename = sFilename;
        }
    }