Index: Core/Common/src/Core.Common.Controls.Swf/TreeViewControls/ITreeView.cs
===================================================================
diff -u -rebe6e048a6c4e9146e883e19e213f41df96aabf1 -rd37e350b3c62d61768313c57c2d8d8d05d22458a
--- Core/Common/src/Core.Common.Controls.Swf/TreeViewControls/ITreeView.cs	(.../ITreeView.cs)	(revision ebe6e048a6c4e9146e883e19e213f41df96aabf1)
+++ Core/Common/src/Core.Common.Controls.Swf/TreeViewControls/ITreeView.cs	(.../ITreeView.cs)	(revision d37e350b3c62d61768313c57c2d8d8d05d22458a)
@@ -14,6 +14,11 @@
         /// </summary>
         event EventHandler SelectedNodeChanged;
 
+        /// <summary>
+        /// Event to notify observers of changes in the tree structure
+        /// </summary>
+        event EventHandler OnUpdate;
+
         event Action BeforeWaitUntilAllEventsAreProcessed;
 
         /// <summary>
Index: Core/Common/src/Core.Common.Controls.Swf/TreeViewControls/TreeView.cs
===================================================================
diff -u -rebe6e048a6c4e9146e883e19e213f41df96aabf1 -rd37e350b3c62d61768313c57c2d8d8d05d22458a
--- Core/Common/src/Core.Common.Controls.Swf/TreeViewControls/TreeView.cs	(.../TreeView.cs)	(revision ebe6e048a6c4e9146e883e19e213f41df96aabf1)
+++ Core/Common/src/Core.Common.Controls.Swf/TreeViewControls/TreeView.cs	(.../TreeView.cs)	(revision d37e350b3c62d61768313c57c2d8d8d05d22458a)
@@ -18,6 +18,7 @@
     public class TreeView : System.Windows.Forms.TreeView, ITreeView
     {
         public event EventHandler SelectedNodeChanged;
+        public event EventHandler OnUpdate;
 
         public event Action BeforeWaitUntilAllEventsAreProcessed;
 
@@ -284,9 +285,22 @@
             if (controller != null)
             {
                 controller.UpdateNode(treeNode, treeNode.Tag);
+                FireOnUpdateEvent(treeNode);
             }
         }
 
+        /// <summary>
+        /// Fires the OnUpdate event with the given <see cref="treeNode"/>.
+        /// </summary>
+        /// <param name="treeNode">The <see cref="ITreeNode"/> to fire an update event for.</param>
+        private void FireOnUpdateEvent(ITreeNode treeNode)
+        {
+            if (OnUpdate != null)
+            {
+                OnUpdate(treeNode, EventArgs.Empty);
+            }
+        }
+
         public void RefreshChildNodes(ITreeNode treeNode)
         {
             if (controller != null)
Index: Core/Common/src/Core.Common.Gui/IGui.cs
===================================================================
diff -u -r0445e854de96c48aaa445849149d7cbc73ab8242 -rd37e350b3c62d61768313c57c2d8d8d05d22458a
--- Core/Common/src/Core.Common.Gui/IGui.cs	(.../IGui.cs)	(revision 0445e854de96c48aaa445849149d7cbc73ab8242)
+++ Core/Common/src/Core.Common.Gui/IGui.cs	(.../IGui.cs)	(revision d37e350b3c62d61768313c57c2d8d8d05d22458a)
@@ -149,6 +149,13 @@
         /// </summary>
         void UpdateTitle();
 
+        /// <summary>
+        /// Update the tool tip for every view currently open. Reasons for doing so 
+        /// include the modification of the tree structure which is reflected in a tool tip.
+        /// </summary>
+        /// <returns></returns>
+        void UpdateToolTips();
+
         #endregion
 
         #region Events
Index: Core/Common/src/Core.Common.Gui/RingtoetsGui.cs
===================================================================
diff -u -r31595e2aa87c2cb7e23fb07cd3f04d219bfd15fd -rd37e350b3c62d61768313c57c2d8d8d05d22458a
--- Core/Common/src/Core.Common.Gui/RingtoetsGui.cs	(.../RingtoetsGui.cs)	(revision 31595e2aa87c2cb7e23fb07cd3f04d219bfd15fd)
+++ Core/Common/src/Core.Common.Gui/RingtoetsGui.cs	(.../RingtoetsGui.cs)	(revision d37e350b3c62d61768313c57c2d8d8d05d22458a)
@@ -372,6 +372,14 @@
             }
         }
 
+        public void UpdateToolTips()
+        {
+            foreach (var view in DocumentViews.AllViews)
+            {
+                SetToolTipForView(view);
+            }
+        }
+
         protected virtual void Dispose(bool disposing)
         {
             if (disposing)
Index: Core/Plugins/src/Core.Plugins.ProjectExplorer/ProjectExplorer.cs
===================================================================
diff -u -r074232b001ecb5ae110c0b95c05264d4372cbfb5 -rd37e350b3c62d61768313c57c2d8d8d05d22458a
--- Core/Plugins/src/Core.Plugins.ProjectExplorer/ProjectExplorer.cs	(.../ProjectExplorer.cs)	(revision 074232b001ecb5ae110c0b95c05264d4372cbfb5)
+++ Core/Plugins/src/Core.Plugins.ProjectExplorer/ProjectExplorer.cs	(.../ProjectExplorer.cs)	(revision d37e350b3c62d61768313c57c2d8d8d05d22458a)
@@ -33,6 +33,7 @@
             treeViewPanel.Controls.Add(ProjectTreeView);
 
             gui.DocumentViews.ActiveViewChanged += DocumentViewsActiveViewChanged;
+            ProjectTreeView.TreeView.OnUpdate += (s,e) => gui.UpdateToolTips();
         }
 
         public ProjectTreeView ProjectTreeView { get; private set; }
Index: Core/Plugins/test/Core.Plugins.CommonTools.Test/TestViewList.cs
===================================================================
diff -u -r41c77f9f36ae74a406fd382187426cc06d2b0200 -rd37e350b3c62d61768313c57c2d8d8d05d22458a
--- Core/Plugins/test/Core.Plugins.CommonTools.Test/TestViewList.cs	(.../TestViewList.cs)	(revision 41c77f9f36ae74a406fd382187426cc06d2b0200)
+++ Core/Plugins/test/Core.Plugins.CommonTools.Test/TestViewList.cs	(.../TestViewList.cs)	(revision d37e350b3c62d61768313c57c2d8d8d05d22458a)
@@ -143,6 +143,11 @@
             throw new NotImplementedException();
         }
 
+        public void UpdateToolTips()
+        {
+            throw new NotImplementedException();
+        }
+
         public IEnumerable<T> GetActiveViews<T>() where T : class, IView
         {
             return views.OfType<T>();
Index: Ringtoets/Common/test/Ringtoets.Common.Forms.Test/NodePresenters/CategoryTreeFolderNodePresenterTest.cs
===================================================================
diff -u -r074232b001ecb5ae110c0b95c05264d4372cbfb5 -rd37e350b3c62d61768313c57c2d8d8d05d22458a
--- Ringtoets/Common/test/Ringtoets.Common.Forms.Test/NodePresenters/CategoryTreeFolderNodePresenterTest.cs	(.../CategoryTreeFolderNodePresenterTest.cs)	(revision 074232b001ecb5ae110c0b95c05264d4372cbfb5)
+++ Ringtoets/Common/test/Ringtoets.Common.Forms.Test/NodePresenters/CategoryTreeFolderNodePresenterTest.cs	(.../CategoryTreeFolderNodePresenterTest.cs)	(revision d37e350b3c62d61768313c57c2d8d8d05d22458a)
@@ -1,8 +1,6 @@
 using System;
 using System.Collections;
 using System.Drawing;
-
-using Core.Common.Controls;
 using Core.Common.Controls.Swf.TreeViewControls;
 using Core.Common.Gui;
 using Core.Common.Gui.ContextMenu;