diff --git a/Import/GacUI.cpp b/Import/GacUI.cpp
index a18fe0f0..14325226 100644
--- a/Import/GacUI.cpp
+++ b/Import/GacUI.cpp
@@ -8429,6 +8429,14 @@ NodeItemProvider
 		{
 			return -2;
 		}
+		if (index == -1)
+		{
+			// Parent returned -1, which means parent has no parent (is a root node)
+			// Check if this parent is OUR root - if not, this is a foreign node
+#define ERROR_MESSAGE_PREFIX L"vl::presentation::controls::tree::NodeItemProvider::CalculateNodeVisibilityIndexInternal(INodeProvider*)#"
+			CHECK_ERROR(parent.Obj() == root->GetRootNode().Obj(), ERROR_MESSAGE_PREFIX L"The node does not belong to the tree associated with this NodeItemProvider.");
+#undef ERROR_MESSAGE_PREFIX
+		}
 
 		vint count = parent->GetChildCount();
 		for (vint i = 0; i < count; i++)
@@ -8451,24 +8459,6 @@ NodeItemProvider
 		return -1;
 	}
 
-	vint NodeItemProvider::CalculateNodeVisibilityIndex(INodeProvider* node)
-	{
-		vint result = CalculateNodeVisibilityIndexInternal(node);
-		return result < 0 ? -1 : result;
-	}
-
-	Ptr<INodeProvider> NodeItemProvider::RequestNode(vint index)
-	{
-		if(root->CanGetNodeByVisibleIndex())
-		{
-			return root->GetNodeByVisibleIndex(index+1);
-		}
-		else
-		{
-			return GetNodeByOffset(root->GetRootNode(), index+1);
-		}
-	}
-
 	NodeItemProvider::NodeItemProvider(Ptr<INodeRootProvider> _root)
 		:root(_root)
 	{
@@ -8485,6 +8475,28 @@ NodeItemProvider
 		return root;
 	}
 
+	Ptr<INodeProvider> NodeItemProvider::RequestNode(vint index)
+	{
+		if (index < 0 || index >= Count())
+		{
+			return nullptr;
+		}
+		else if (root->CanGetNodeByVisibleIndex())
+		{
+			return root->GetNodeByVisibleIndex(index + 1);
+		}
+		else
+		{
+			return GetNodeByOffset(root->GetRootNode(), index + 1);
+		}
+	}
+
+	vint NodeItemProvider::CalculateNodeVisibilityIndex(INodeProvider* node)
+	{
+		vint result = CalculateNodeVisibilityIndexInternal(node);
+		return result < 0 ? -1 : result;
+	}
+
 	vint NodeItemProvider::Count()
 	{
 		return root->GetRootNode()->CalculateTotalVisibleNodes()-1;
@@ -8492,20 +8504,20 @@ NodeItemProvider
 
 	WString NodeItemProvider::GetTextValue(vint itemIndex)
 	{
-		if (auto node = RequestNode(itemIndex))
-		{
-			return root->GetTextValue(node.Obj());
-		}
-		return L"";
+#define ERROR_MESSAGE_PREFIX L"vl::presentation::controls::tree::NodeItemProvider::GetTextValue(vint)#"
+		CHECK_ERROR(0 <= itemIndex && itemIndex < Count(), ERROR_MESSAGE_PREFIX L"Index out of range.");
+		auto node = RequestNode(itemIndex);
+		return root->GetTextValue(node.Obj());
+#undef ERROR_MESSAGE_PREFIX
 	}
 
 	description::Value NodeItemProvider::GetBindingValue(vint itemIndex)
 	{
-		if (auto node = RequestNode(itemIndex))
-		{
-			return root->GetBindingValue(node.Obj());
-		}
-		return Value();
+#define ERROR_MESSAGE_PREFIX L"vl::presentation::controls::tree::NodeItemProvider::GetBindingValue(vint)#"
+		CHECK_ERROR(0 <= itemIndex && itemIndex < Count(), ERROR_MESSAGE_PREFIX L"Index out of range.");
+		auto node = RequestNode(itemIndex);
+		return root->GetBindingValue(node.Obj());
+#undef ERROR_MESSAGE_PREFIX
 	}
 
 	IDescriptable* NodeItemProvider::RequestView(const WString& identifier)
@@ -8627,7 +8639,7 @@ MemoryNodeProvider
 	void MemoryNodeProvider::OnChildTotalVisibleNodesChanged(vint offset)
 	{
 		totalVisibleNodeCount+=offset;
-		if(parent)
+		if(parent && parent->GetExpanding())
 		{
 			parent->OnChildTotalVisibleNodesChanged(offset);
 		}
@@ -15547,39 +15559,6 @@ TreeViewItem
 TreeViewItemRootProvider
 ***********************************************************************/
 
-	Ptr<GuiImageData> TreeViewItemRootProvider::GetNodeImage(INodeProvider* node)
-	{
-		MemoryNodeProvider* memoryNode=dynamic_cast<MemoryNodeProvider*>(node);
-		if(memoryNode)
-		{
-			Ptr<TreeViewItem> data=memoryNode->GetData().Cast<TreeViewItem>();
-			if(data)
-			{
-				return data->image;
-			}
-		}
-		return 0;
-	}
-
-	WString TreeViewItemRootProvider::GetTextValue(INodeProvider* node)
-	{
-		MemoryNodeProvider* memoryNode = dynamic_cast<MemoryNodeProvider*>(node);
-		if (memoryNode)
-		{
-			Ptr<TreeViewItem> data = memoryNode->GetData().Cast<TreeViewItem>();
-			if (data)
-			{
-				return data->text;
-			}
-		}
-		return L"";
-	}
-
-	description::Value TreeViewItemRootProvider::GetBindingValue(INodeProvider* node)
-	{
-		return Value::From(GetTreeViewData(node));
-	}
-
 	TreeViewItemRootProvider::TreeViewItemRootProvider()
 	{
 	}
@@ -15588,18 +15567,6 @@ TreeViewItemRootProvider
 	{
 	}
 
-	IDescriptable* TreeViewItemRootProvider::RequestView(const WString& identifier)
-	{
-		if(identifier==ITreeViewItemView::Identifier)
-		{
-			return (ITreeViewItemView*)this;
-		}
-		else
-		{
-			return MemoryNodeRootProvider::RequestView(identifier);
-		}
-	}
-
 	Ptr<TreeViewItem> TreeViewItemRootProvider::GetTreeViewData(INodeProvider* node)
 	{
 		MemoryNodeProvider* memoryNode=GetMemoryNode(node);
@@ -15630,6 +15597,51 @@ TreeViewItemRootProvider
 			memoryNode->NotifyDataModified();
 		}
 	}
+
+	Ptr<GuiImageData> TreeViewItemRootProvider::GetNodeImage(INodeProvider* node)
+	{
+		MemoryNodeProvider* memoryNode = dynamic_cast<MemoryNodeProvider*>(node);
+		if (memoryNode)
+		{
+			Ptr<TreeViewItem> data = memoryNode->GetData().Cast<TreeViewItem>();
+			if (data)
+			{
+				return data->image;
+			}
+		}
+		return 0;
+	}
+
+	WString TreeViewItemRootProvider::GetTextValue(INodeProvider* node)
+	{
+		MemoryNodeProvider* memoryNode = dynamic_cast<MemoryNodeProvider*>(node);
+		if (memoryNode)
+		{
+			Ptr<TreeViewItem> data = memoryNode->GetData().Cast<TreeViewItem>();
+			if (data)
+			{
+				return data->text;
+			}
+		}
+		return L"";
+	}
+
+	description::Value TreeViewItemRootProvider::GetBindingValue(INodeProvider* node)
+	{
+		return Value::From(GetTreeViewData(node));
+	}
+
+	IDescriptable* TreeViewItemRootProvider::RequestView(const WString& identifier)
+	{
+		if (identifier == ITreeViewItemView::Identifier)
+		{
+			return (ITreeViewItemView*)this;
+		}
+		else
+		{
+			return MemoryNodeRootProvider::RequestView(identifier);
+		}
+	}
 }
 
 /***********************************************************************
diff --git a/Import/GacUI.h b/Import/GacUI.h
index aa618459..62e02f03 100644
--- a/Import/GacUI.h
+++ b/Import/GacUI.h
@@ -1363,9 +1363,7 @@ NodeItemProvider
 		void							OnItemExpanded(INodeProvider* node)override;
 		void							OnItemCollapsed(INodeProvider* node)override;
 		vint							CalculateNodeVisibilityIndexInternal(INodeProvider* node);
-		vint							CalculateNodeVisibilityIndex(INodeProvider* node)override;
 		
-		Ptr<INodeProvider>				RequestNode(vint index)override;
 	public:
 		/// <summary>Create an item provider using a node root provider.</summary>
 		/// <param name="_root">The node root provider.</param>
@@ -1375,6 +1373,14 @@ NodeItemProvider
 		/// <summary>Get the owned node root provider.</summary>
 		/// <returns>The node root provider.</returns>
 		Ptr<INodeRootProvider>			GetRoot();
+
+		// ===================== list::INodeItemView =====================
+
+		Ptr<INodeProvider>				RequestNode(vint index)override;
+		vint							CalculateNodeVisibilityIndex(INodeProvider* node)override;
+
+		// ===================== list::IItemProvider =====================
+
 		vint							Count()override;
 		WString							GetTextValue(vint itemIndex)override;
 		description::Value				GetBindingValue(vint itemIndex)override;
@@ -11265,18 +11271,11 @@ TreeViewItemRootProvider
 		, public virtual ITreeViewItemView
 		, public Description<TreeViewItemRootProvider>
 	{
-	protected:
-
-		Ptr<GuiImageData>				GetNodeImage(INodeProvider* node)override;
-		WString							GetTextValue(INodeProvider* node)override;
-		description::Value				GetBindingValue(INodeProvider* node)override;
 	public:
 		/// <summary>Create a item root provider.</summary>
 		TreeViewItemRootProvider();
 		~TreeViewItemRootProvider();
 
-		IDescriptable*					RequestView(const WString& identifier)override;
-
 		/// <summary>Get the <see cref="TreeViewItem"/> object from a node.</summary>
 		/// <returns>The <see cref="TreeViewItem"/> object.</returns>
 		/// <param name="node">The node to get the tree view item.</param>
@@ -11288,6 +11287,16 @@ TreeViewItemRootProvider
 		/// <summary>Notify the tree view control that the node is changed. This is required when content in a <see cref="TreeViewItem"/> is modified, but both <see cref="SetTreeViewData"/> or [M:vl.presentation.controls.tree.MemoryNodeProvider.SetData] are not called.</summary>
 		/// <param name="node">The node.</param>
 		void							UpdateTreeViewData(INodeProvider* node);
+
+		// ===================== list::ITreeViewItemView =====================
+
+		Ptr<GuiImageData>				GetNodeImage(INodeProvider* node)override;
+		WString							GetTextValue(INodeProvider* node)override;
+		description::Value				GetBindingValue(INodeProvider* node)override;
+
+		// ===================== list::IItemProvider =====================
+
+		IDescriptable*					RequestView(const WString& identifier)override;
 	};
 }
 
diff --git a/Tutorial/GacUI_HelloWorlds/UIRes/Xml.bin.x64 b/Tutorial/GacUI_HelloWorlds/UIRes/Xml.bin.x64
index 23363ef4..6b0c048f 100644
Binary files a/Tutorial/GacUI_HelloWorlds/UIRes/Xml.bin.x64 and b/Tutorial/GacUI_HelloWorlds/UIRes/Xml.bin.x64 differ
diff --git a/Tutorial/GacUI_HelloWorlds/UIRes/Xml.bin.x86 b/Tutorial/GacUI_HelloWorlds/UIRes/Xml.bin.x86
index b65fe364..7783c123 100644
Binary files a/Tutorial/GacUI_HelloWorlds/UIRes/Xml.bin.x86 and b/Tutorial/GacUI_HelloWorlds/UIRes/Xml.bin.x86 differ