Index: Core/Common/src/Core.Common.Base/Observable.cs
===================================================================
diff -u -r2a90c0c1be6114f72af65c42f0a6f334b30e4755 -r275f55bd5c011375598d201bd95c02cb8da63dba
--- Core/Common/src/Core.Common.Base/Observable.cs	(.../Observable.cs)	(revision 2a90c0c1be6114f72af65c42f0a6f334b30e4755)
+++ Core/Common/src/Core.Common.Base/Observable.cs	(.../Observable.cs)	(revision 275f55bd5c011375598d201bd95c02cb8da63dba)
@@ -2,7 +2,7 @@
 
 namespace Core.Common.Base
 {
-    public class Observable : IObservable
+    public abstract class Observable : IObservable
     {
         private readonly IList<IObserver> observers = new List<IObserver>();
 
Index: Core/Common/src/Core.Common.Controls.Swf/TreeViewControls/TreeView.cs
===================================================================
diff -u -r113fd0fac19ed2f327ae9faa016f25660785b5ce -r275f55bd5c011375598d201bd95c02cb8da63dba
--- Core/Common/src/Core.Common.Controls.Swf/TreeViewControls/TreeView.cs	(.../TreeView.cs)	(revision 113fd0fac19ed2f327ae9faa016f25660785b5ce)
+++ Core/Common/src/Core.Common.Controls.Swf/TreeViewControls/TreeView.cs	(.../TreeView.cs)	(revision 275f55bd5c011375598d201bd95c02cb8da63dba)
@@ -292,6 +292,9 @@
             }
         }
 
+        /// <summary>
+        /// The method wraps <see cref="DeleteSelectedNodeData"/> with a couple of messaging boxes.
+        /// </summary>
         public void TryDeleteSelectedNodeData()
         {
             if (!SelectedNodeCanDelete())
Index: Core/Common/test/Core.Common.Base.Tests/Controls/Swf/TreeViewControls/TreeViewTest.cs
===================================================================
diff -u -r67074d560004857fc12988e881533d9371828ddb -r275f55bd5c011375598d201bd95c02cb8da63dba
--- Core/Common/test/Core.Common.Base.Tests/Controls/Swf/TreeViewControls/TreeViewTest.cs	(.../TreeViewTest.cs)	(revision 67074d560004857fc12988e881533d9371828ddb)
+++ Core/Common/test/Core.Common.Base.Tests/Controls/Swf/TreeViewControls/TreeViewTest.cs	(.../TreeViewTest.cs)	(revision 275f55bd5c011375598d201bd95c02cb8da63dba)
@@ -6,12 +6,13 @@
 using System.Windows.Forms;
 using Core.Common.Base.Tests.TestObjects;
 using Core.Common.Controls;
+using Core.Common.Controls.Swf;
 using Core.Common.Controls.Swf.TreeViewControls;
 using Core.Common.TestUtils;
-using Core.Common.Utils.Reflection;
 using NUnit.Framework;
 using Rhino.Mocks;
 using SharpTestsEx;
+using MessageBox = Core.Common.Controls.Swf.MessageBox;
 using TreeView = Core.Common.Controls.Swf.TreeViewControls.TreeView;
 
 namespace Core.Common.Base.Tests.Controls.Swf.TreeViewControls
@@ -324,45 +325,58 @@
         [Test]
         public void DeletedNodeMovesSelectionToItsParentNode()
         {
-            var treeView = new TreeView
+            using (var treeView = new TreeView())
             {
-                NodePresenters =
+                treeView.NodePresenters.Add(new ParentNodePresenter());
+                treeView.NodePresenters.Add(new ChildNodePresenter());
+            
+                var parent = new Parent()
                 {
-                    new ParentNodePresenter(), // DynamicParentNodePresenter(),
-                    new ChildNodePresenter()
-                }
-            };
+                    Name = "Parent"
+                };
+                var child = new Child()
+                {
+                    Name = "Child"
+                };
+                var grandchild = new Child()
+                {
+                    Name = "GrandChild"
+                };
+                parent.Children.Add(child);
+                child.Children.Add(grandchild);
 
-            var parent = new Parent() { Name = "Parent"};
-            var child = new Child() { Name = "Child" };
-            var grandchild = new Child() { Name = "GrandChild" };
-            parent.Children.Add(child);
-            child.Children.Add(grandchild);
+                treeView.Data = parent;
 
-            treeView.Data = parent;
+                try
+                {
+                    WindowsFormsTestHelper.Show(treeView); // show it to make sure that expand / refresh node really loads nodes.
 
-            try
-            {
-                WindowsFormsTestHelper.Show(treeView); // show it to make sure that expand / refresh node really loads nodes.
+                    treeView.ExpandAll();
 
-                treeView.ExpandAll();
-                treeView.Refresh();
+                    treeView.SelectedNode = treeView.GetNodeByTag(grandchild);
+                    MessageBox.CustomMessageBox = new MessageBoxAlwaysYes();
+                    treeView.TryDeleteSelectedNodeData();
 
-                treeView.SelectedNode = treeView.GetNodeByTag(grandchild);
+                    treeView.ExpandAll();
 
-                TypeUtils.CallPrivateMethod(treeView, "DeleteSelectedNodeData");
-
-                treeView.ExpandAll();
-                treeView.Refresh();
-
-                Assert.AreEqual(treeView.SelectedNode, treeView.GetNodeByTag(child));
+                    Assert.AreEqual(treeView.SelectedNode, treeView.GetNodeByTag(child));
+                }
+                finally
+                {
+                    WindowsFormsTestHelper.CloseAll();
+                }
             }
-            finally 
+        }
+
+        class MessageBoxAlwaysYes : IMessageBox
+        {
+            public DialogResult Show(string text, string caption, MessageBoxButtons buttons)
             {
-                WindowsFormsTestHelper.CloseAll();
+                return DialogResult.OK; 
             }
         }
 
+
         [Test]
         public void TreeViewUpdateOnManyPropertyChangesShouldBeFast()
         {
Index: Core/Common/test/Core.Common.Base.Tests/TestObjects/Child.cs
===================================================================
diff -u -r113fd0fac19ed2f327ae9faa016f25660785b5ce -r275f55bd5c011375598d201bd95c02cb8da63dba
--- Core/Common/test/Core.Common.Base.Tests/TestObjects/Child.cs	(.../Child.cs)	(revision 113fd0fac19ed2f327ae9faa016f25660785b5ce)
+++ Core/Common/test/Core.Common.Base.Tests/TestObjects/Child.cs	(.../Child.cs)	(revision 275f55bd5c011375598d201bd95c02cb8da63dba)
@@ -5,38 +5,14 @@
 namespace Core.Common.Base.Tests.TestObjects
 {
     [Entity]
-    public class Child : IObservable
+    public class Child : Observable
     {
-        private readonly IList<IObserver> observers = new List<IObserver>();
-
         public Child()
         {
             Children = new EventedList<Child>();
         }
 
         public string Name { get; set; }
         public IList<Child> Children { get; set; }
-
-        #region IObservable
-
-        public void Attach(IObserver observer)
-        {
-            observers.Add(observer);
-        }
-
-        public void Detach(IObserver observer)
-        {
-            observers.Remove(observer);
-        }
-
-        public void NotifyObservers()
-        {
-            foreach (var observer in observers)
-            {
-                observer.UpdateObserver();
-            }
-        }
-
-        #endregion
     }
 }
\ No newline at end of file
Index: Core/Common/test/Core.Common.Base.Tests/TestObjects/ChildNodePresenter.cs
===================================================================
diff -u -r113fd0fac19ed2f327ae9faa016f25660785b5ce -r275f55bd5c011375598d201bd95c02cb8da63dba
--- Core/Common/test/Core.Common.Base.Tests/TestObjects/ChildNodePresenter.cs	(.../ChildNodePresenter.cs)	(revision 113fd0fac19ed2f327ae9faa016f25660785b5ce)
+++ Core/Common/test/Core.Common.Base.Tests/TestObjects/ChildNodePresenter.cs	(.../ChildNodePresenter.cs)	(revision 275f55bd5c011375598d201bd95c02cb8da63dba)
@@ -33,8 +33,6 @@
                 }
             }
 
-            
-
             return true;
         }
 
Index: Core/Common/test/Core.Common.Base.Tests/TestObjects/Parent.cs
===================================================================
diff -u -r2a90c0c1be6114f72af65c42f0a6f334b30e4755 -r275f55bd5c011375598d201bd95c02cb8da63dba
--- Core/Common/test/Core.Common.Base.Tests/TestObjects/Parent.cs	(.../Parent.cs)	(revision 2a90c0c1be6114f72af65c42f0a6f334b30e4755)
+++ Core/Common/test/Core.Common.Base.Tests/TestObjects/Parent.cs	(.../Parent.cs)	(revision 275f55bd5c011375598d201bd95c02cb8da63dba)
@@ -2,32 +2,9 @@
 
 namespace Core.Common.Base.Tests.TestObjects
 {
-    public class Parent : IObservable
+    public class Parent : Observable
     {
-        private readonly IList<IObserver> observers = new List<IObserver>();
         public readonly IList<Child> Children = new List<Child>();
         public string Name { get; set; }
-
-        #region IObservable
-
-        public void Attach(IObserver observer)
-        {
-            observers.Add(observer);
-        }
-
-        public void Detach(IObserver observer)
-        {
-            observers.Remove(observer);
-        }
-
-        public void NotifyObservers()
-        {
-            foreach (var observer in observers)
-            {
-                observer.UpdateObserver();
-            }
-        }
-
-        #endregion
     }
 }
\ No newline at end of file