Add issue Remember a deselected blog in preview

- Sometimes a blog download can run very long and even have not any new media to preview, other blogs are downloaded in parallel, but their preview isn't shown because the long running blog was the first one.
- If another blog/row is chosen in the manager view, the previous/deselected blog is remembered as unwanted. Every time a new blog starts downloading, it's preview is shown although the remembered blog is still downloading.

src/TumblThree/TumblThree.Applications/Controllers/QueueController.cs

@@ -228,7 +228,9 @@ private void CrawlerServiceActiveItemsCollectionChanged(object sender, NotifyCol
         {
             if (_crawlerService.ActiveItems.Count > 0)
             {
-                _detailsService.UpdateBlogPreview(_crawlerService.ActiveItems.OrderByDescending(x => x.Blog.LastPreviewShown).Take(1).Select(x => x.Blog).ToArray());
+                IBlog[] blogs = _crawlerService.ActiveItems.OrderByDescending(x => x.Blog.LastPreviewShown)
+                    .SkipWhile(x => _crawlerService.ActiveItems.Count > 1 && x.Blog == _crawlerService.LastDeselectedPreview).Take(1).Select(x => x.Blog).ToArray();
+                _detailsService.UpdateBlogPreview(blogs);
             }
         }
 

src/TumblThree/TumblThree.Applications/Services/CrawlerService.cs

@@ -11,6 +11,7 @@
 using System.Windows.Data;
 using System.Windows.Input;
 using TumblThree.Domain.Models;
+using TumblThree.Domain.Models.Blogs;
 using TumblThree.Domain.Queue;
 
 namespace TumblThree.Applications.Services
@@ -53,6 +54,7 @@ public class CrawlerService : Model, ICrawlerService
         private Timer _timer;
         private string _isTextVis;
         private bool _isToolTipActive;
+        private IBlog _lastDeselectedPreview;
 
         [ImportingConstructor]
         public CrawlerService(IShellService shellService)
@@ -254,6 +256,12 @@ public string NewBlogUrl
             set => SetProperty(ref _newBlogUrl, value);
         }
 
+        public IBlog LastDeselectedPreview
+        {
+            get => _lastDeselectedPreview;
+            set => SetProperty(ref _lastDeselectedPreview, value);
+        }
+
         public int ActiveCollectionId
         {
             get

src/TumblThree/TumblThree.Applications/Services/ICrawlerService.cs

@@ -5,6 +5,7 @@
 using System.Threading.Tasks;
 using System.Waf.Foundation;
 using System.Windows.Input;
+using TumblThree.Domain.Models.Blogs;
 using TumblThree.Domain.Queue;
 
 namespace TumblThree.Applications.Services
@@ -54,6 +55,8 @@ public interface ICrawlerService : INotifyPropertyChanged
 
         string NewBlogUrl { get; set; }
 
+        IBlog LastDeselectedPreview { get; set; }
+
         int ActiveCollectionId { get; set; }
 
         IReadOnlyObservableList<QueueListItem> ActiveItems { get; }

src/TumblThree/TumblThree.Presentation/DesignData/MockCrawlerService.cs

@@ -89,6 +89,8 @@ public void UpdateCollectionsList(bool isInit)
 
         public string NewBlogUrl { get; set; }
 
+        public IBlog LastDeselectedPreview { get; set; }
+
         public int ActiveCollectionId { get; set; }
 
         public Guava.RateLimiter.RateLimiter TimeconstraintApi { get; set; }

src/TumblThree/TumblThree.Presentation/Views/ManagerView.xaml.cs

@@ -44,6 +44,10 @@ private void SelectionChanged(object sender, SelectionChangedEventArgs e)
         {
             ViewModel.SelectionService.RemoveRange(e.RemovedItems.Cast<IBlog>());
             ViewModel.SelectionService.AddRange(e.AddedItems.Cast<IBlog>());
+            if (e.RemovedItems.Count == 1)
+            {
+                ViewModel.CrawlerService.LastDeselectedPreview = (IBlog)e.RemovedItems[0];
+            }
         }
 
         private ManagerViewModel ViewModel