diff --git a/Import/GacUI.cpp b/Import/GacUI.cpp
index 644c250a..7f06bd90 100644
--- a/Import/GacUI.cpp
+++ b/Import/GacUI.cpp
@@ -12860,21 +12860,32 @@ NodeItemProvider
 
 				void NodeItemProvider::OnBeforeItemModified(INodeProvider* parentNode, vint start, vint count, vint newCount)
 				{
-					offsetBeforeChildModified=0;
+					vint offset = 0;
 					vint base=CalculateNodeVisibilityIndexInternal(parentNode);
 					if(base!=-2 && parentNode->GetExpanding())
 					{
 						for(vint i=0;i<count;i++)
 						{
 							INodeProvider* child=parentNode->GetChild(start+i);
-							offsetBeforeChildModified+=child->CalculateTotalVisibleNodes();
+							offset+=child->CalculateTotalVisibleNodes();
 							child->Release();
 						}
 					}
+					offsetBeforeChildModifieds.Set(parentNode, offset);
 				}
 
 				void NodeItemProvider::OnAfterItemModified(INodeProvider* parentNode, vint start, vint count, vint newCount)
 				{
+					vint offsetBeforeChildModified = 0;
+					{
+						vint index = offsetBeforeChildModifieds.Keys().IndexOf(parentNode);
+						if (index != -1)
+						{
+							offsetBeforeChildModified = offsetBeforeChildModifieds.Values().Get(index);
+							offsetBeforeChildModifieds.Remove(parentNode);
+						}
+					}
+
 					vint base=CalculateNodeVisibilityIndexInternal(parentNode);
 					if(base!=-2 && parentNode->GetExpanding())
 					{
diff --git a/Import/GacUI.h b/Import/GacUI.h
index 47e0a42e..caed0ea2 100644
--- a/Import/GacUI.h
+++ b/Import/GacUI.h
@@ -12716,10 +12716,12 @@ GuiVirtualTreeListControl NodeProvider
 					, protected virtual INodeItemView
 					, public Description<NodeItemProvider>
 				{
+					typedef collections::Dictionary<INodeProvider*, vint>			NodeIntMap;
 				protected:
 					Ptr<INodeRootProvider>			root;
 					INodeItemPrimaryTextView*		nodeItemPrimaryTextView;
-					vint							offsetBeforeChildModified;
+					NodeIntMap						offsetBeforeChildModifieds;
+					
 
 					INodeProvider*					GetNodeByOffset(INodeProvider* provider, vint offset);
 					void							OnAttached(INodeRootProvider* provider)override;
diff --git a/Import/GacUIReflection.cpp b/Import/GacUIReflection.cpp
index 4d399b9f..4a4fcef6 100644
--- a/Import/GacUIReflection.cpp
+++ b/Import/GacUIReflection.cpp
@@ -1867,6 +1867,8 @@ Type Declaration
 				CLASS_MEMBER_PROPERTY_FAST(TitleBar)
 
 				CLASS_MEMBER_METHOD(MoveToScreenCenter, NO_PARAMETER)
+				CLASS_MEMBER_METHOD(ShowModal, { L"owner" _ L"callback" })
+				CLASS_MEMBER_METHOD(ShowModalAndDelete, { L"owner" _ L"callback" })
 			END_CLASS_MEMBER(GuiWindow)
 
 			BEGIN_INTERFACE_MEMBER(GuiWindow::IStyleController)
diff --git a/Tools/GacGen.exe b/Tools/GacGen.exe
index 3d7d6a08..c767c999 100644
Binary files a/Tools/GacGen.exe and b/Tools/GacGen.exe differ
diff --git a/Tutorial/GacUI_Controls/AddressBook/Main.cpp b/Tutorial/GacUI_Controls/AddressBook/Main.cpp
index adc29575..22f2322d 100644
--- a/Tutorial/GacUI_Controls/AddressBook/Main.cpp
+++ b/Tutorial/GacUI_Controls/AddressBook/Main.cpp
@@ -14,8 +14,11 @@ int CALLBACK WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLi
 Ptr<GuiImageData> folderImage;
 Ptr<GuiImageData> contactImage;
 
+class ViewModel;
+
 class Category : public Object, public ICategory
 {
+	friend class ViewModel;
 protected:
 	ICategory*									parent;
 	WString										name;
@@ -59,11 +62,7 @@ public:
 	StaticCategory()
 		:Category(nullptr)
 	{
-	}
-
-	WString GetName()override
-	{
-		return L"My Address Book";
+		name = L"My Address Book";
 	}
 };
 
@@ -137,10 +136,21 @@ public:
 
 	void AddCategory(WString name)
 	{
+		if (auto current = dynamic_cast<Category*>(selectedCategory.Obj()))
+		{
+			auto category = new Category(current);
+			category->name = name;
+			current->folders.Add(category);
+		}
 	}
 
 	void RemoveCategory()
 	{
+		if (auto parent = dynamic_cast<Category*>(selectedCategory->GetParent()))
+		{
+			parent->folders.Remove(selectedCategory.Obj());
+			SetSelectedCategory(nullptr);
+		}
 	}
 };
 
diff --git a/Tutorial/GacUI_Controls/AddressBook/UI/Resource.xml b/Tutorial/GacUI_Controls/AddressBook/UI/Resource.xml
index 801c9efb..7fd8a6e3 100644
--- a/Tutorial/GacUI_Controls/AddressBook/UI/Resource.xml
+++ b/Tutorial/GacUI_Controls/AddressBook/UI/Resource.xml
@@ -76,7 +76,7 @@
     <Instance name="MainWindowResource">
       <Instance ref.Class="demo::MainWindow">
         <ref.Parameter Name="ViewModel" Class="demo::IViewModel"/>
-        <Window Text="AddressBook" ClientSize="x:480 y:320">
+        <Window ref.Name="self" Text="AddressBook" ClientSize="x:480 y:320">
           <att.BoundsComposition-set PreferredMinSize="x:480 y:320"/>
 
           <att.ViewModel-set>
@@ -85,7 +85,21 @@
 
           <ToolstripCommand ref.Name="commandNewFolder" Image-uri="res://Images/NewFolder">
             <att.Enabled-bind>ViewModel.SelectedCategory is not null</att.Enabled-bind>
-            <ev.Executed-eval>{}</ev.Executed-eval>
+            <ev.Executed-eval>
+              <![CDATA[
+                {
+                  var window = new demo::NewFolderWindow*();
+                  window.MoveToScreenCenter();
+                  window.ShowModalAndDelete(self, func():void
+                  {
+                    if (window.Ready)
+                    {
+                      ViewModel.AddCategory(window.FolderName);
+                    }
+                  });
+                }
+              ]]>
+            </ev.Executed-eval>
           </ToolstripCommand>
           <ToolstripCommand ref.Name="commandDeleteFolder" Image-uri="res://Images/Delete">
             <att.Enabled-bind>ViewModel.SelectedCategory is null ? false : ViewModel.SelectedCategory.Parent is not null</att.Enabled-bind>
@@ -204,5 +218,52 @@
         </Window>
       </Instance>
     </Instance>
+    
+    <Instance name="NewFolderWindowResource">
+      <Instance ref.CodeBehind="false" ref.Class="demo::NewFolderWindow">
+        <ref.Property Name="FolderName" Type="string" Value=""/>
+        <ref.Property Name="Ready" Type="bool" Value="true"/>
+        <Window ref.Name="self" Text="New Folder" ClientSize="x:240 y:120" MaximizedBox="false" MinimizedBox="false" SizeBox="false">
+          <att.FolderName-bind>textBoxName.Text</att.FolderName-bind>
+          
+          <Table CellPadding="5" AlignmentToParent="left:0 top:0 right:0 bottom:0">
+            <att.Rows>
+              <CellOption>composeType:MinSize</CellOption>
+              <CellOption>composeType:Percentage percentage:1.0</CellOption>
+              <CellOption>composeType:MinSize</CellOption>
+            </att.Rows>
+            <att.Columns>
+              <CellOption>composeType:MinSize</CellOption>
+              <CellOption>composeType:Percentage percentage:1.0</CellOption>
+              <CellOption>composeType:MinSize</CellOption>
+              <CellOption>composeType:MinSize</CellOption>
+            </att.Columns>
+
+            <Cell Site="row:0 column:0" InternalMargin="top:6">
+              <Label Text="Name:"/>
+            </Cell>
+
+            <Cell Site="row:0 column:1 columnSpan:3">
+              <DocumentTextBox ref.Name="textBoxName" EditMode="Editable" Text="New Folder">
+                <att.BoundsComposition-set AlignmentToParent="left:0 top:0 right:0 bottom:0"/>
+              </DocumentTextBox>
+            </Cell>
+
+            <Cell Site="row:2 column:2">
+              <Button Text="OK">
+                <att.BoundsComposition-set AlignmentToParent="left:0 top:0 right:0 bottom:0" PreferredMinSize="x:60"/>
+                <ev.Clicked-eval>{ self.Close(); }</ev.Clicked-eval>
+              </Button>
+            </Cell>
+            <Cell Site="row:2 column:3">
+              <Button Text="Cancel">
+                <att.BoundsComposition-set AlignmentToParent="left:0 top:0 right:0 bottom:0" PreferredMinSize="x:60"/>
+                <ev.Clicked-eval>{ self.Ready = false; self.Close(); }</ev.Clicked-eval>
+              </Button>
+            </Cell>
+          </Table>
+        </Window>
+      </Instance>
+    </Instance>
   </Folder>
 </Resource>
\ No newline at end of file
diff --git a/Tutorial/GacUI_Controls/AddressBook/UI/Source/DemoPartialClasses.cpp b/Tutorial/GacUI_Controls/AddressBook/UI/Source/DemoPartialClasses.cpp
index ad63d08d..47dad4f7 100644
--- a/Tutorial/GacUI_Controls/AddressBook/UI/Source/DemoPartialClasses.cpp
+++ b/Tutorial/GacUI_Controls/AddressBook/UI/Source/DemoPartialClasses.cpp
@@ -10,6 +10,34 @@ DO NOT MODIFY
 
 #include "Demo.h"
 
+namespace demo
+{
+	// #region CLASS_MEMBER_GUIEVENT_HANDLER (DO NOT PUT OTHER CONTENT IN THIS #region.)
+
+	void NewFolderWindow::OnCreate()
+	{
+	}
+
+	void NewFolderWindow::OnDestroy()
+	{
+	}
+
+	// #endregion CLASS_MEMBER_GUIEVENT_HANDLER
+
+	NewFolderWindow::NewFolderWindow()
+	{
+		InitializeComponents();
+		OnCreate();
+	}
+
+	NewFolderWindow::~NewFolderWindow()
+	{
+		OnDestroy();
+		ClearSubscriptions();
+	}
+}
+
+
 namespace vl
 {
 	namespace reflection
@@ -20,6 +48,7 @@ namespace vl
 			IMPL_CPP_TYPE_INFO(demo::ICategory)
 			IMPL_CPP_TYPE_INFO(demo::IViewModel)
 			IMPL_CPP_TYPE_INFO(demo::MainWindow)
+			IMPL_CPP_TYPE_INFO(demo::NewFolderWindow)
 
 			BEGIN_CLASS_MEMBER(demo::ICategory)
 				CLASS_MEMBER_BASE(vl::reflection::IDescriptable)
@@ -62,6 +91,16 @@ namespace vl
 				CLASS_MEMBER_PROPERTY_READONLY_FAST(ViewModel)
 			END_CLASS_MEMBER(demo::MainWindow)
 
+			BEGIN_CLASS_MEMBER(demo::NewFolderWindow)
+				CLASS_MEMBER_BASE(vl::presentation::controls::GuiWindow)
+				CLASS_MEMBER_CONSTRUCTOR(demo::NewFolderWindow*(), NO_PARAMETER)
+
+				CLASS_MEMBER_EVENT(FolderNameChanged)
+				CLASS_MEMBER_PROPERTY_EVENT_FAST(FolderName, FolderNameChanged)
+				CLASS_MEMBER_EVENT(ReadyChanged)
+				CLASS_MEMBER_PROPERTY_EVENT_FAST(Ready, ReadyChanged)
+			END_CLASS_MEMBER(demo::NewFolderWindow)
+
 			#undef _
 
 			class DemoResourceLoader : public Object, public ITypeLoader
@@ -72,6 +111,7 @@ namespace vl
 					ADD_TYPE_INFO(demo::ICategory)
 					ADD_TYPE_INFO(demo::IViewModel)
 					ADD_TYPE_INFO(demo::MainWindow)
+					ADD_TYPE_INFO(demo::NewFolderWindow)
 				}
 
 				void Unload(ITypeManager* manager)
diff --git a/Tutorial/GacUI_Controls/AddressBook/UI/Source/DemoPartialClasses.h b/Tutorial/GacUI_Controls/AddressBook/UI/Source/DemoPartialClasses.h
index e9056e2d..dd9196bd 100644
--- a/Tutorial/GacUI_Controls/AddressBook/UI/Source/DemoPartialClasses.h
+++ b/Tutorial/GacUI_Controls/AddressBook/UI/Source/DemoPartialClasses.h
@@ -18,6 +18,7 @@ namespace demo
 	class ICategory;
 	class IViewModel;
 	class MainWindow;
+	class NewFolderWindow;
 
 	class ICategory : public virtual vl::reflection::IDescriptable, public vl::reflection::Description<ICategory>
 	{
@@ -58,6 +59,7 @@ namespace demo
 		vl::presentation::controls::GuiToolstripCommand* commandSmallIcon;
 		vl::presentation::controls::GuiToolstripCommand* commandTile;
 		vl::presentation::controls::GuiBindableListView* listViewContacts;
+		vl::presentation::controls::GuiWindow* self;
 		vl::presentation::controls::GuiBindableTreeView* treeViewFolders;
 
 		void InitializeComponents(Ptr<demo::IViewModel> ViewModel)
@@ -76,6 +78,7 @@ namespace demo
 				GUI_INSTANCE_REFERENCE(commandSmallIcon);
 				GUI_INSTANCE_REFERENCE(commandTile);
 				GUI_INSTANCE_REFERENCE(listViewContacts);
+				GUI_INSTANCE_REFERENCE(self);
 				GUI_INSTANCE_REFERENCE(treeViewFolders);
 			}
 			else
@@ -98,6 +101,7 @@ namespace demo
 			,commandSmallIcon(0)
 			,commandTile(0)
 			,listViewContacts(0)
+			,self(0)
 			,treeViewFolders(0)
 		{
 		}
@@ -108,6 +112,66 @@ namespace demo
 		}
 	};
 
+	template<typename TImpl>
+	class NewFolderWindow_ : public vl::presentation::controls::GuiWindow, public vl::presentation::GuiInstancePartialClass<vl::presentation::controls::GuiWindow>, public vl::reflection::Description<TImpl>
+	{
+		friend struct vl::reflection::description::CustomTypeDescriptorSelector<TImpl>;
+	private:
+		vl::WString FolderName_;
+		bool Ready_;
+	protected:
+		vl::presentation::controls::GuiWindow* self;
+		vl::presentation::controls::GuiDocumentLabel* textBoxName;
+
+		void InitializeComponents()
+		{
+			if (InitializeFromResource())
+			{
+				GUI_INSTANCE_REFERENCE(self);
+				GUI_INSTANCE_REFERENCE(textBoxName);
+			}
+			else
+			{
+			}
+		}
+	public:
+		NewFolderWindow_()
+			:vl::presentation::GuiInstancePartialClass<vl::presentation::controls::GuiWindow>(L"demo::NewFolderWindow")
+			,vl::presentation::controls::GuiWindow(vl::presentation::theme::GetCurrentTheme()->CreateWindowStyle())
+			,self(0)
+			,textBoxName(0)
+		{
+			this->FolderName_ = vl::reflection::description::UnboxValue<vl::WString>(vl::reflection::description::Value::From(L"", reflection::description::GetTypeDescriptor<vl::WString>()));
+			this->Ready_ = vl::reflection::description::UnboxValue<bool>(vl::reflection::description::Value::From(L"true", reflection::description::GetTypeDescriptor<bool>()));
+		}
+
+		vl::Event<void()> FolderNameChanged;
+
+		vl::WString GetFolderName()
+		{
+			return FolderName_;
+		}
+
+		void SetFolderName(vl::WString value)
+		{
+			FolderName_ = value;
+			FolderNameChanged();
+		}
+
+		vl::Event<void()> ReadyChanged;
+
+		bool GetReady()
+		{
+			return Ready_;
+		}
+
+		void SetReady(bool value)
+		{
+			Ready_ = value;
+			ReadyChanged();
+		}
+	};
+
 }
 namespace vl
 {
@@ -118,9 +182,29 @@ namespace vl
 			DECL_TYPE_INFO(demo::ICategory)
 			DECL_TYPE_INFO(demo::IViewModel)
 			DECL_TYPE_INFO(demo::MainWindow)
+			DECL_TYPE_INFO(demo::NewFolderWindow)
 
 		}
 	}
 }
+namespace demo
+{
+	class NewFolderWindow : public demo::NewFolderWindow_<demo::NewFolderWindow>
+	{
+		friend class demo::NewFolderWindow_<demo::NewFolderWindow>;
+		friend struct vl::reflection::description::CustomTypeDescriptorSelector<demo::NewFolderWindow>;
+	protected:
+
+		// #region CLASS_MEMBER_GUIEVENT_HANDLER (DO NOT PUT OTHER CONTENT IN THIS #region.)
+		void OnCreate();
+		void OnDestroy();
+		// #endregion CLASS_MEMBER_GUIEVENT_HANDLER
+	public:
+		NewFolderWindow();
+		~NewFolderWindow();
+	};
+}
+
+
 
 #endif
diff --git a/Tutorial/GacUI_Controls/UIRes/AddressBook.bin b/Tutorial/GacUI_Controls/UIRes/AddressBook.bin
index 1f015709..5f863679 100644
Binary files a/Tutorial/GacUI_Controls/UIRes/AddressBook.bin and b/Tutorial/GacUI_Controls/UIRes/AddressBook.bin differ