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);
        }