print out thumbnail loading status to console

Program.cs

@@ -378,6 +378,8 @@ public class Game : GameWindow {
   int VertexBufferObject;
   int ElementBufferObject;
   int VertexArrayObject;
+  readonly object thumbnailsLoadedLock = new();
+  int thumbnailsLoaded = 0;
   List<Photo> allPhotos = new();
   List<Photo> photos = new();
   HashSet<Photo> loadedImages = new();
@@ -720,9 +722,18 @@ public class Game : GameWindow {
   }
 
   private async void LoadThumbnailsAsync() {
+    List<Task> tasks = new();
     foreach (Photo p in allPhotos) {
-      await Task.Run( () => { p.LoadThumbnailAsync(geometry.ThumbnailSize); });
+      tasks.Add(Task.Run( () => {
+        p.LoadThumbnailAsync(geometry.ThumbnailSize);
+        lock (thumbnailsLoadedLock) {
+          thumbnailsLoaded++;
+          Console.WriteLine(thumbnailsLoaded);
+        }
+      }));
     }
+    Console.WriteLine("TASKS: " + tasks.Count);
+    await Task.WhenAll(tasks).ContinueWith(t => { Console.WriteLine("done????"); });
   }
 
   // To find the JPEG compression level of a file from the command line: