#1803: Make sure that the assembly list is always restored.

ILSpy/Docking/DockWorkspace.cs

@@ -102,6 +102,11 @@ namespace ICSharpCode.ILSpy.Docking
 			}
 		}
 
+		internal void EnsureUnclosablePanes()
+		{
+			ToolPanes.Add(AssemblyListPaneModel.Instance);
+		}
+
 		protected void RaisePropertyChanged([CallerMemberName] string propertyName = null)
 		{
 			PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));

ILSpy/MainWindow.xaml.cs

@@ -134,6 +134,8 @@ namespace ICSharpCode.ILSpy
 				serializer.LayoutSerializationCallback -= DockWorkspace.Instance.LayoutSerializationCallback;
 			}
 
+			DockWorkspace.Instance.EnsureUnclosablePanes();
+
 			sessionSettings.FilterSettings.PropertyChanged += filterSettings_PropertyChanged;
 
 			InitMainMenu();