diff --git a/Import/GacUI.cpp b/Import/GacUI.cpp
index 41bf5696..9a211fac 100644
--- a/Import/GacUI.cpp
+++ b/Import/GacUI.cpp
@@ -4327,7 +4327,7 @@ GuiWindow
 					{
 						WindowClosed.Detach(container->handler);
 						container->handler = nullptr;
-						GetNativeWindow()->SetParent(0);
+						GetNativeWindow()->SetParent(nullptr);
 						callback();
 						owner->SetEnabled(true);
 						owner->SetActivated();
@@ -4507,11 +4507,23 @@ GuiPopup
 			{
 				auto window = GetNativeWindow();
 				UpdateClientSizeAfterRendering(window->GetBounds().GetSize());
+
+				INativeWindow* controlWindow = nullptr;
 				switch (popupType)
 				{
-				case 2: window->SetParent(popupInfo._2.controlWindow); break;
-				case 3: window->SetParent(popupInfo._3.controlWindow); break;
-				case 4: window->SetParent(popupInfo._4.controlWindow); break;
+				case 2: controlWindow = popupInfo._2.controlWindow; break;
+				case 3: controlWindow = popupInfo._3.controlWindow; break;
+				case 4: controlWindow = popupInfo._4.controlWindow; break;
+				}
+
+				if (controlWindow)
+				{
+					window->SetParent(controlWindow);
+					window->SetTopMost(controlWindow->GetTopMost());
+				}
+				else
+				{
+					window->SetTopMost(false);
 				}
 				ShowDeactivated();
 			}
@@ -9848,10 +9860,13 @@ ItemProviderBase
 
 				void ItemProviderBase::InvokeOnItemModified(vint start, vint count, vint newCount)
 				{
+					CHECK_ERROR(!callingOnItemModified, L"ItemProviderBase::InvokeOnItemModified(vint, vint, vint)#Canning modify the observable data source during its item modified event, which will cause this event to be executed recursively.");
+					callingOnItemModified = true;
 					for (vint i = 0; i < callbacks.Count(); i++)
 					{
 						callbacks[i]->OnItemModified(start, count, newCount);
 					}
+					callingOnItemModified = false;
 				}
 
 				ItemProviderBase::ItemProviderBase()
diff --git a/Import/GacUI.h b/Import/GacUI.h
index 31978360..e2f88594 100644
--- a/Import/GacUI.h
+++ b/Import/GacUI.h
@@ -12476,6 +12476,7 @@ Predefined ItemProvider
 				protected:
 					collections::List<GuiListControl::IItemProviderCallback*>	callbacks;
 					vint														editingCounter = 0;
+					bool														callingOnItemModified = false;
 
 					virtual void								InvokeOnItemModified(vint start, vint count, vint newCount);
 				public:
diff --git a/Import/GacUIWindows.cpp b/Import/GacUIWindows.cpp
index cf819d4c..092d48d1 100644
--- a/Import/GacUIWindows.cpp
+++ b/Import/GacUIWindows.cpp
@@ -9259,7 +9259,6 @@ WindowsController
 				Dictionary<HWND, WindowsForm*>		windows;
 				INativeWindow*						mainWindow;
 				HWND								mainWindowHandle;
-				vint								handleMessageLevelCounter = 0;
 
 				WindowsCallbackService				callbackService;
 				WindowsResourceService				resourceService;
@@ -9304,7 +9303,6 @@ WindowsController
 				bool HandleMessage(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam, LRESULT& result)
 				{
 					bool skipDefaultProcedure=false;
-					handleMessageLevelCounter++;
 					{
 						vint index = windows.Keys().IndexOf(hwnd);
 						if (index != -1)
@@ -9346,11 +9344,6 @@ WindowsController
 							PostQuitMessage(0);
 						}
 					}
-					handleMessageLevelCounter--;
-					if (handleMessageLevelCounter == 0)
-					{
-						asyncService.ExecuteAsyncTasks();
-					}
 					return skipDefaultProcedure;
 				}
 
diff --git a/Import/Vlpp.h b/Import/Vlpp.h
index b5cd0d66..93df90fb 100644
--- a/Import/Vlpp.h
+++ b/Import/Vlpp.h
@@ -5558,8 +5558,6 @@ CompareEnumerable
 				{
 					return 1;
 				}
-				ator->Next();
-				btor->Next();
 			}
 			return 0;
 		}
diff --git a/Tools/CppMerge.exe b/Tools/CppMerge.exe
index ab4792b4..1105467e 100644
Binary files a/Tools/CppMerge.exe and b/Tools/CppMerge.exe differ
diff --git a/Tools/GacGen32.exe b/Tools/GacGen32.exe
index d0a5999e..b8158afc 100644
Binary files a/Tools/GacGen32.exe and b/Tools/GacGen32.exe differ
diff --git a/Tools/GacGen64.exe b/Tools/GacGen64.exe
index b49f5b96..31eb923e 100644
Binary files a/Tools/GacGen64.exe and b/Tools/GacGen64.exe differ
diff --git a/Tutorial/GacUI_HelloWorlds/UIRes/Xml.bin.x64 b/Tutorial/GacUI_HelloWorlds/UIRes/Xml.bin.x64
index d1557273..a423102c 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 392e2295..5d2e86d7 100644
Binary files a/Tutorial/GacUI_HelloWorlds/UIRes/Xml.bin.x86 and b/Tutorial/GacUI_HelloWorlds/UIRes/Xml.bin.x86 differ