diff --git a/include/nana/gui/widgets/widget.hpp b/include/nana/gui/widgets/widget.hpp
index 18163f61..0288388e 100644
--- a/include/nana/gui/widgets/widget.hpp
+++ b/include/nana/gui/widgets/widget.hpp
@@ -31,7 +31,7 @@ namespace nana
 		: nana::noncopyable, nana::nonmovable
 	{
 		friend class detail::widget_notifier_interface;
-		class notifier;
+		class inner_widget_notifier;
 		typedef void(*dummy_bool_type)(widget* (*)(const widget&));
 	public:
 		virtual ~widget() = default;
diff --git a/source/gui/detail/window_manager.cpp b/source/gui/detail/window_manager.cpp
index 4ba1c3a2..e9581fd1 100644
--- a/source/gui/detail/window_manager.cpp
+++ b/source/gui/detail/window_manager.cpp
@@ -326,6 +326,9 @@ namespace detail
 			std::lock_guard<decltype(mutex_)> lock(mutex_);
 			if (impl_->wd_register.available(wd) == false)	return;
 
+			if (wd->flags.destroying)
+				return;
+
 			if(wd->other.category == category::root_tag::value)
 			{
 				auto &brock = bedrock::instance();
@@ -340,13 +343,15 @@ namespace detail
 					if(wd->flags.modal || (wd->owner == nullptr) || wd->owner->flags.take_active)
 						native_interface::activate_owner(wd->root);
 
-					//Close should detach the drawer and send destroy signal to widget object.
-					//Otherwise, when a widget object is been deleting in other thread by delete operator, the object will be destroyed
-					//before the window_manager destroyes the window, and then, window_manager detaches the
-					//non-existing drawer_trigger which is destroyed by destruction of widget. Crash!
-					wd->drawer.detached();
-
-					wd->widget_notifier->destroy();
+					if (!wd->flags.destroying)
+					{
+						//Close should detach the drawer and send destroy signal to widget object.
+						//Otherwise, when a widget object is been deleting in other thread by delete operator, the object will be destroyed
+						//before the window_manager destroyes the window, and then, window_manager detaches the
+						//non-existing drawer_trigger which is destroyed by destruction of widget. Crash!
+						wd->drawer.detached();
+						wd->widget_notifier->destroy();
+					}
 
 					native_interface::close_window(wd->root);
 				}
diff --git a/source/gui/widgets/tabbar.cpp b/source/gui/widgets/tabbar.cpp
index 6532bf6e..8b82c6d0 100644
--- a/source/gui/widgets/tabbar.cpp
+++ b/source/gui/widgets/tabbar.cpp
@@ -1440,7 +1440,6 @@ namespace nana
 				private:
 					void _m_calc_metrics(graph_reference graph, std::forward_list<item>& items)
 					{
-						const auto height_px = graph.height();
 						std::vector<unsigned> pxs;
 
 						unsigned pixels = 0;
diff --git a/source/gui/widgets/widget.cpp b/source/gui/widgets/widget.cpp
index af853b38..39a2ac57 100644
--- a/source/gui/widgets/widget.cpp
+++ b/source/gui/widgets/widget.cpp
@@ -22,10 +22,10 @@ namespace nana
 
 	//class widget
 	//@brief:The definition of class widget
-		class widget::notifier: public detail::widget_notifier_interface
+		class widget::inner_widget_notifier : public detail::widget_notifier_interface
 		{
 		public:
-			notifier(widget& wdg)
+			inner_widget_notifier(widget& wdg)
 				: wdg_(wdg)
 			{}
 
@@ -246,7 +246,7 @@ namespace nana
 
 		std::unique_ptr<::nana::detail::widget_notifier_interface> widget::_m_wdg_notifier()
 		{
-			return std::unique_ptr<::nana::detail::widget_notifier_interface>(new notifier(*this));
+			return std::unique_ptr<::nana::detail::widget_notifier_interface>(new inner_widget_notifier(*this));
 		}
 
 		void widget::_m_complete_creation()
@@ -348,7 +348,7 @@ namespace nana
 	{
 		std::unique_ptr<widget_notifier_interface> widget_notifier_interface::get_notifier(widget* wdg)
 		{
-			return std::unique_ptr<widget_notifier_interface>(new widget::notifier(*wdg));
+			return std::unique_ptr<widget_notifier_interface>(new widget::inner_widget_notifier(*wdg));
 		}
 	}
 }//end namespace nana