private void GenerateItems() { var fav = new MailFolder() { FolderName = "Favorites" }; var myFolder = new MailFolder() { FolderName = "My Folder" }; var inbox = new MailFolder() { FolderName = "Inbox", MailsCount = 20 }; var drafts = new MailFolder() { FolderName = "Drafts", MailsCount = 5 }; var deleted = new MailFolder() { FolderName = "Deleted Items" }; var sent = new MailFolder() { FolderName = "Sent Items" }; var sales = new MailFolder() { FolderName = "Sales Report", MailsCount = 4 }; var marketing = new MailFolder() { FolderName = "Marketing Reports", MailsCount = 6 }; var outbox = new MailFolder() { FolderName = "Outbox" }; var calender = new MailFolder() { FolderName = "Calender" }; var birthday = new MailFolder() { FolderName = "Birthdays" }; var holiday = new MailFolder() { FolderName = "Holidays" }; var groups = new MailFolder() { FolderName = "Groups" }; var developmentTeam = new MailFolder() { FolderName = "Development Team", MailsCount = 11 }; var salesTeam = new MailFolder() { FolderName = "Sales Team", MailsCount = 5 }; var testingTeam = new MailFolder() { FolderName = "Testing Team", MailsCount = 33 }; fav.SubFolder = new ObservableCollection <MailFolder> { new MailFolder() { FolderName = "Sales Report", MailsCount = 4 }, new MailFolder() { FolderName = "Sent Items" }, new MailFolder() { FolderName = "Marketing Reports", MailsCount = 6 } }; myFolder.SubFolder = new ObservableCollection <MailFolder> { inbox, drafts, deleted, sent, sales, marketing, outbox }; calender.SubFolder = new ObservableCollection <MailFolder> { birthday, holiday }; groups.SubFolder = new ObservableCollection <MailFolder> { developmentTeam, salesTeam, testingTeam }; this.Folders = new ObservableCollection <MailFolder>(); Folders.Add(fav); Folders.Add(myFolder); Folders.Add(calender); Folders.Add(groups); }