private void btnNext_Click(object sender, RoutedEventArgs e)
        {
            EnumerateControls.LockGUI<Start>(this);
            this.url = txtLink.Text.Trim(); 
            int result = checkUrlLogic(url);

            switch (result)
            {
                case 0: MessageBox.Show("Invalid youtube url!", "YouTube Downloader");
                    break;
                case 1: playlist = new Playlist(this, url);
                    playlist.ShowsNavigationUI = false;
                    if (playlist.Error != true)
                        this.NavigationService.Navigate(playlist);
                    else
                        playlist = null;
                    break;
                case 2: List<WBlinkinfo> singleLink = new List<WBlinkinfo>();
                    singleLink.Add(new WBlinkinfo(null, url, true));                    
                    SaveLocation saveLocation = new SaveLocation(this, singleLink);
                    saveLocation.ShowsNavigationUI = false;
                    if (saveLocation.Error != true)
                        this.NavigationService.Navigate(saveLocation);
                    else
                        saveLocation = null;
                    break;
            }
            EnumerateControls.UnlockGui<Start>(this);
        }
        private void btnNext_Click(object sender, RoutedEventArgs e)
        {
            if (!ObsColWB.All(x => x.IsChecked == false))
            {
                EnumerateControls.LockGUI<Playlist>(this);
                for (int c = 0; c < ObsColWB.Count; c++)
                {
                    if (ObsColWB[c].IsChecked == true)
                        wb1linkInfo[c].SelForDload = true;
                    else
                        wb1linkInfo[c].SelForDload = false;
                }
                saveLocation = new SaveLocation(this, wb1linkInfo);
                saveLocation.ShowsNavigationUI = false;
                if (saveLocation.Error != true)
                    this.NavigationService.Navigate(saveLocation);

                else
                    saveLocation = null;
                EnumerateControls.UnlockGui<Playlist>(this);
            }
            else
                lblMessage.Content = "No Links Selected!";
        }