diff --git a/include/nana/audio/detail/audio_stream.hpp b/include/nana/audio/detail/audio_stream.hpp
index 5fe9d39c..d148f98f 100644
--- a/include/nana/audio/detail/audio_stream.hpp
+++ b/include/nana/audio/detail/audio_stream.hpp
@@ -59,7 +59,7 @@ namespace nana{	namespace audio{
 				unsigned cksize;
 			};
 		public:
-			bool open(const nana::string& file);
+			bool open(const std::string& file);
 			void close();
 			bool empty() const;
 			const wave_spec::format_chunck & format() const;
diff --git a/include/nana/audio/player.hpp b/include/nana/audio/player.hpp
index 24378214..3fc1acca 100644
--- a/include/nana/audio/player.hpp
+++ b/include/nana/audio/player.hpp
@@ -14,10 +14,10 @@ namespace nana{	namespace audio
 		struct implementation;
 	public:
 		player();
-		player(const nana::string& file);
+		player(const std::string& file);
 		~player();
 
-		bool open(const nana::string& file);
+		bool open(const std::string& file);
 		void play();
 		void close();
 	private:
diff --git a/include/nana/gui/msgbox.hpp b/include/nana/gui/msgbox.hpp
index 8c5fc5a6..af5a1437 100644
--- a/include/nana/gui/msgbox.hpp
+++ b/include/nana/gui/msgbox.hpp
@@ -55,10 +55,10 @@ namespace nana
 		void clear();
 
 		/// Writes a string to the buffer.
-		msgbox & operator<<(const nana::string&);
+		msgbox & operator<<(const std::wstring&);
 
 		/// Writes a string to the buffer.
-		msgbox & operator<<(const nana::char_t*);
+		msgbox & operator<<(const wchar_t*);
 
 		/// Writes a string to the buffer.
 		msgbox & operator<<(const nana::charset&);
diff --git a/include/nana/gui/notifier.hpp b/include/nana/gui/notifier.hpp
index c6eea9da..a557fd45 100644
--- a/include/nana/gui/notifier.hpp
+++ b/include/nana/gui/notifier.hpp
@@ -55,9 +55,9 @@ namespace nana
 		notifier(window);
 		~notifier();
 		void close();
-		void text(const nana::string&);
-		void icon(const nana::string& icon_file);
-		void insert_icon(const nana::string& icon_file);
+		void text(const ::std::string&);
+		void icon(const ::std::string& icon_file);
+		void insert_icon(const ::std::string& icon_file);
 		void period(unsigned millisecond);
 		detail::notifier_events& events();
 		window handle() const;
diff --git a/include/nana/gui/programming_interface.hpp b/include/nana/gui/programming_interface.hpp
index dfa4e610..f1caf871 100644
--- a/include/nana/gui/programming_interface.hpp
+++ b/include/nana/gui/programming_interface.hpp
@@ -140,7 +140,7 @@ namespace API
 
 	void exit();
 
-	nana::string transform_shortkey_text(nana::string text, nana::string::value_type &shortkey, nana::string::size_type *skpos);
+	std::string transform_shortkey_text(std::string text, wchar_t &shortkey, std::string::size_type *skpos);
 	bool register_shortkey(window, unsigned long);
 	void unregister_shortkey(window);
 
diff --git a/include/nana/gui/widgets/menu.hpp b/include/nana/gui/widgets/menu.hpp
index 512d30d7..9a182a08 100644
--- a/include/nana/gui/widgets/menu.hpp
+++ b/include/nana/gui/widgets/menu.hpp
@@ -56,7 +56,7 @@ namespace nana
 
 				//Default constructor initializes the item as a splitter
 				menu_item_type();
-				menu_item_type(nana::string, const event_fn_t&);
+				menu_item_type(std::string, const event_fn_t&);
 
 				struct
 				{
@@ -66,7 +66,7 @@ namespace nana
 				}flags;
 
 				menu_type		*sub_menu{nullptr};
-				nana::string	text;
+				std::string	text;
 				event_fn_t	functor;
 				checks			style{checks::none};
 				paint::image	image;
@@ -134,7 +134,7 @@ namespace nana
 		~menu();
 
 			/// Appends an item to the menu.
-		item_proxy	append(const nana::string& text, const event_fn_t& callback= event_fn_t());
+		item_proxy	append(const std::string& text, const event_fn_t& callback= event_fn_t());
 		void		append_splitter();
 		void clear();								///< Erases all of the items.
 		/// Closes the menu. It does not destroy the menu; just close the window for the menu.
diff --git a/include/nana/gui/widgets/menubar.hpp b/include/nana/gui/widgets/menubar.hpp
index 8e7270bc..0422b6a0 100644
--- a/include/nana/gui/widgets/menubar.hpp
+++ b/include/nana/gui/widgets/menubar.hpp
@@ -108,7 +108,7 @@ namespace nana
 		menubar(window);						///< Create a menubar at the top of the specified window.
 		~menubar();
 		void create(window);					///< Create a menubar at the top of the specified window.
-		menu& push_back(const nana::string&);	///< Appends a new (empty) menu.
+		menu& push_back(const std::string&);	///< Appends a new (empty) menu.
 		menu& at(size_t index) const;		    ///< Gets the menu specified by index.
 		std::size_t length() const;		        ///< Number of menus.
 	private:
diff --git a/include/nana/gui/widgets/skeletons/text_token_stream.hpp b/include/nana/gui/widgets/skeletons/text_token_stream.hpp
index 4f936400..873b23cd 100644
--- a/include/nana/gui/widgets/skeletons/text_token_stream.hpp
+++ b/include/nana/gui/widgets/skeletons/text_token_stream.hpp
@@ -79,7 +79,7 @@ namespace nana{ namespace widgets{	namespace skeletons
 			return idstr_;
 		}
 
-		const std::pair<nana::string, nana::string>& binary() const
+		const std::pair<std::wstring, std::wstring>& binary() const
 		{
 			return binary_;
 		}
@@ -412,13 +412,13 @@ namespace nana{ namespace widgets{	namespace skeletons
 			}
 		}
 	private:
-		const ::nana::char_t * iptr_;
-		const ::nana::char_t * endptr_;
+		const wchar_t * iptr_;
+		const wchar_t * endptr_;
 		const bool	format_enabled_;
 		bool	format_state_{false};
 
-		::nana::string idstr_;
-		std::pair<nana::string, nana::string> binary_;
+		std::wstring idstr_;
+		std::pair<std::wstring, std::wstring> binary_;
 		token revert_token_{token::eof};
 	};
 
@@ -458,7 +458,7 @@ namespace nana{ namespace widgets{	namespace skeletons
 
 		virtual bool	is_text() const = 0;
 		virtual bool	is_whitespace() const = 0;
-		virtual const nana::string& text() const = 0;
+		virtual const std::wstring& text() const = 0;
 		virtual void measure(graph_reference) = 0;
 		virtual void nontext_render(graph_reference, int x, int y) = 0;
 		virtual const nana::size & size() const = 0;
@@ -470,7 +470,7 @@ namespace nana{ namespace widgets{	namespace skeletons
 		: public data
 	{
 	public:
-		data_text(const nana::string& s)
+		data_text(const std::wstring& s)
 			: str_(s)
 		{}
 	private:
@@ -484,7 +484,7 @@ namespace nana{ namespace widgets{	namespace skeletons
 			return false;
 		}
 
-		virtual const nana::string& text() const override
+		virtual const std::wstring& text() const override
 		{
 			return str_;
 		}
@@ -513,7 +513,7 @@ namespace nana{ namespace widgets{	namespace skeletons
 			return ascent_;
 		}
 	private:
-		nana::string str_;
+		std::wstring str_;
 		nana::size	size_;
 		std::size_t ascent_;
 	};
@@ -522,7 +522,7 @@ namespace nana{ namespace widgets{	namespace skeletons
 		: public data
 	{
 	public:
-		data_image(const nana::string& imgpath, const nana::size & sz, std::size_t limited)
+		data_image(const std::wstring& imgpath, const nana::size & sz, std::size_t limited)
 			: image_(imgpath)//, limited_(limited)
 		{
 			size_ = image_.size();
@@ -562,7 +562,7 @@ namespace nana{ namespace widgets{	namespace skeletons
 			return false;
 		}
 
-		virtual const nana::string& text() const override
+		virtual const std::wstring& text() const override
 		{
 			return str_;
 		}
@@ -589,7 +589,7 @@ namespace nana{ namespace widgets{	namespace skeletons
 			return size_.height;
 		}
 	private:
-		nana::string str_;
+		std::wstring str_;
 		nana::paint::image image_;
 		nana::size size_;
 	};
@@ -626,7 +626,7 @@ namespace nana{ namespace widgets{	namespace skeletons
 			fblocks_.clear();
 		}
 
-		void parse(const nana::string& s, bool format_enabled)
+		void parse(const std::wstring& s, bool format_enabled)
 		{
 			close();
 
@@ -893,7 +893,7 @@ namespace nana{ namespace widgets{	namespace skeletons
 			return fbp;
 		}
 
-		void _m_data_factory(token tk, const nana::string& idstr, fblock* fp, std::deque<value>& line)
+		void _m_data_factory(token tk, const std::wstring& idstr, fblock* fp, std::deque<value>& line)
 		{
 			value v;
 			v.fblock_ptr = fp;
@@ -926,7 +926,7 @@ namespace nana{ namespace widgets{	namespace skeletons
 
 		struct attr_image_tag
 		{
-			nana::string	path;
+			std::wstring	path;
 			nana::size		size;
 			std::size_t		limited;
 
diff --git a/include/nana/paint/graphics.hpp b/include/nana/paint/graphics.hpp
index be093425..301b6f3f 100644
--- a/include/nana/paint/graphics.hpp
+++ b/include/nana/paint/graphics.hpp
@@ -90,13 +90,14 @@ namespace nana
 			void typeface(const font&);						///< Selects a specified font type into the graphics object.
 			font typeface() const;
 			::nana::size	text_extent_size(const ::std::string&) const;
-			::nana::size	text_extent_size(const char_t*) const;    ///< Computes the width and height of the specified string of text.
+			::nana::size	text_extent_size(const char*, std::size_t len) const;
+			::nana::size	text_extent_size(const wchar_t*) const;    ///< Computes the width and height of the specified string of text.
 			::nana::size	text_extent_size(const ::std::wstring&) const;    ///< Computes the width and height of the specified string of text.
-			::nana::size	text_extent_size(const char_t*, std::size_t length) const;    ///< Computes the width and height of the specified string of text with the specified length.
+			::nana::size	text_extent_size(const wchar_t*, std::size_t length) const;    ///< Computes the width and height of the specified string of text with the specified length.
 			::nana::size	text_extent_size(const ::std::wstring&, std::size_t length) const;    ///< Computes the width and height of the specified string of text with the specified length.
-			::nana::size	glyph_extent_size(const char_t*, std::size_t length, std::size_t begin, std::size_t end) const;
+			::nana::size	glyph_extent_size(const wchar_t*, std::size_t length, std::size_t begin, std::size_t end) const;
 			::nana::size	glyph_extent_size(const ::std::wstring&, std::size_t length, std::size_t begin, std::size_t end) const;
-			bool glyph_pixels(const char_t *, std::size_t length, unsigned* pxbuf) const;
+			bool glyph_pixels(const wchar_t *, std::size_t length, unsigned* pxbuf) const;
 			::nana::size	bidi_extent_size(const std::wstring&) const;
 			::nana::size	bidi_extent_size(const std::string&) const;
 
@@ -154,10 +155,10 @@ namespace nana
 			void string(const point&, const std::string& text_utf8);
 			void string(const point&, const std::string& text_utf8, const color&);
 
-			void string(point, const char_t*, std::size_t len);
-			void string(const point&, const char_t*);
-			void string(const point&, const ::nana::string&);
-			void string(const point&, const ::nana::string&, const color&);
+			void string(point, const wchar_t*, std::size_t len);
+			void string(const point&, const wchar_t*);
+			void string(const point&, const ::std::wstring&);
+			void string(const point&, const ::std::wstring&, const color&);
 
 			void line(const point&, const point&);
 			void line(const point&, const point&, const color&);
diff --git a/source/audio/detail/audio_stream.cpp b/source/audio/detail/audio_stream.cpp
index 902911a0..3446ac04 100644
--- a/source/audio/detail/audio_stream.cpp
+++ b/source/audio/detail/audio_stream.cpp
@@ -6,9 +6,9 @@ namespace nana{	namespace audio
 	namespace detail
 	{
 		//class audio_stream
-			bool audio_stream::open(const nana::string& file)
+			bool audio_stream::open(const std::string& file)
 			{
-				fs_.open(static_cast<std::string>(charset(file)), std::ios::binary);
+				fs_.open(to_osmbstr(file), std::ios::binary);
 				if(fs_)
 				{
 					wave_spec::master_riff_chunk riff;
diff --git a/source/audio/player.cpp b/source/audio/player.cpp
index 5941c073..013b331e 100644
--- a/source/audio/player.cpp
+++ b/source/audio/player.cpp
@@ -17,7 +17,7 @@ namespace nana{	namespace audio
 			: impl_(new implementation)
 		{}
 
-		player::player(const nana::string& file)
+		player::player(const std::string& file)
 			: impl_(new implementation)
 		{
 			open(file);
@@ -28,7 +28,7 @@ namespace nana{	namespace audio
 			delete impl_;
 		}
 
-		bool player::open(const nana::string& file)
+		bool player::open(const std::string& file)
 		{
 			if(impl_->stream.open(file))
 			{
diff --git a/source/gui/msgbox.cpp b/source/gui/msgbox.cpp
index 55bbeb4c..4cd36b0f 100644
--- a/source/gui/msgbox.cpp
+++ b/source/gui/msgbox.cpp
@@ -108,7 +108,7 @@ namespace nana
 				_m_icon(ico);
 			}
 
-			void prompt(const nana::string& text)
+			void prompt(const std::string& text)
 			{
 				if(text.size())
 				{
@@ -376,23 +376,15 @@ namespace nana
 		sstream_.clear();
 	}
 
-	msgbox & msgbox::operator<<(const nana::string& str)
+	msgbox & msgbox::operator<<(const std::wstring& str)
 	{
-#if defined(NANA_UNICODE)
-		sstream_<<static_cast<std::string>(nana::charset(str));
-#else
-		sstream_<<str;
-#endif
+		sstream_ << to_osmbstr(to_utf8(str));
 		return *this;
 	}
 
-	msgbox & msgbox::operator<<(const nana::char_t* str)
+	msgbox & msgbox::operator<<(const wchar_t* str)
 	{
-#if defined(NANA_UNICODE)
-		sstream_<<static_cast<std::string>(nana::charset(str));;
-#else
-		sstream_<<str;
-#endif
+		sstream_ << to_osmbstr(to_utf8(str));
 		return *this;
 	}
 
diff --git a/source/gui/notifier.cpp b/source/gui/notifier.cpp
index 242b0334..4e98e037 100644
--- a/source/gui/notifier.cpp
+++ b/source/gui/notifier.cpp
@@ -299,10 +299,10 @@ namespace nana
 		impl_->native_handle = nullptr;
 	}
 
-	void notifier::text(const nana::string& str)
+	void notifier::text(const std::string& str)
 	{
 #if defined(NANA_WINDOWS)
-		NOTIFYICONDATA icon_data;
+		NOTIFYICONDATAW icon_data;
 		memset(&icon_data, 0, sizeof icon_data);
 		icon_data.cbSize = sizeof icon_data;
 		icon_data.hWnd = reinterpret_cast<HWND>(impl_->native_handle);
@@ -310,18 +310,18 @@ namespace nana
 		icon_data.uFlags = NIF_MESSAGE | NIF_TIP;
 		icon_data.uCallbackMessage = nana::detail::messages::tray;
 
-		strcpy(icon_data.szTip, str.data());
+		std::wcscpy(icon_data.szTip, to_wstring(str).c_str());
 
 		::Shell_NotifyIcon(impl_->icon_added ? NIM_MODIFY : NIM_ADD, &icon_data);
 		impl_->icon_added = true;
 #endif
 	}
 
-	void notifier::icon(const nana::string& icon_file)
+	void notifier::icon(const std::string& icon_file)
 	{
 #if defined(NANA_WINDOWS)
 		auto pre_icon = impl_->icon_handle;
-		auto ico = (HICON)::LoadImage(0, icon_file.data(), IMAGE_ICON, 0, 0, LR_LOADFROMFILE);
+		auto ico = (HICON)::LoadImageW(0, to_wstring(icon_file).data(), IMAGE_ICON, 0, 0, LR_LOADFROMFILE);
 		if (ico)
 		{
 			impl_->icon_handle = ico;
@@ -333,10 +333,10 @@ namespace nana
 #endif	
 	}
 
-	void notifier::insert_icon(const nana::string& icon_file)
+	void notifier::insert_icon(const std::string& icon_file)
 	{
 #if defined(NANA_WINDOWS)
-		auto icon = (HICON)::LoadImage(0, icon_file.data(), IMAGE_ICON, 0, 0, LR_LOADFROMFILE);
+		auto icon = (HICON)::LoadImage(0, to_wstring(icon_file).data(), IMAGE_ICON, 0, 0, LR_LOADFROMFILE);
 		impl_->icons.push_back(icon);
 #endif
 	}
diff --git a/source/gui/programming_interface.cpp b/source/gui/programming_interface.cpp
index 0888ab41..ccf37675 100644
--- a/source/gui/programming_interface.cpp
+++ b/source/gui/programming_interface.cpp
@@ -336,14 +336,14 @@ namespace API
 	//@param, text: the text is transformed.
 	//@param, shortkey: the character which indicates a short key.
 	//@param, skpos: retrives the shortkey position if it is not a null_ptr;
-	nana::string transform_shortkey_text(nana::string text, nana::string::value_type &shortkey, nana::string::size_type *skpos)
+	std::string transform_shortkey_text(std::string text, wchar_t &shortkey, std::string::size_type *skpos)
 	{
 		shortkey = 0;
-		nana::string::size_type off = 0;
+		std::string::size_type off = 0;
 		while(true)
 		{
-			nana::string::size_type pos = text.find_first_of('&', off);
-			if(pos != nana::string::npos)
+			auto pos = text.find_first_of('&', off);
+			if(pos != std::wstring::npos)
 			{
 				text.erase(pos, 1);
 				if(shortkey == 0 && pos < text.length())
diff --git a/source/gui/widgets/button.cpp b/source/gui/widgets/button.cpp
index bbd36e19..0a35ba1b 100644
--- a/source/gui/widgets/button.cpp
+++ b/source/gui/widgets/button.cpp
@@ -212,11 +212,9 @@ namespace nana{	namespace drawerbase
 
 		void trigger::_m_draw_title(graph_reference graph, bool enabled)
 		{
-			std::wstring text = ::nana::charset(wdg_->caption(), ::nana::unicode::utf8);
-
-			std::wstring::value_type shortkey;
-			std::wstring::size_type shortkey_pos;
-			std::wstring str = API::transform_shortkey_text(text, shortkey, &shortkey_pos);
+			wchar_t shortkey;
+			std::string::size_type shortkey_pos;
+			std::wstring str = to_wstring(API::transform_shortkey_text(wdg_->caption(), shortkey, &shortkey_pos));
 
 			nana::size ts = graph.text_extent_size(str);
 			nana::size gsize = graph.size();
@@ -237,7 +235,7 @@ namespace nana{	namespace drawerbase
 
 			unsigned omitted_pixels = gsize.width - icon_sz.width;
 			std::size_t txtlen = str.size();
-			const nana::char_t* txtptr = str.c_str();
+			const auto txtptr = str.c_str();
 			if(ts.width)
 			{
 				nana::paint::text_renderer tr(graph);
@@ -513,14 +511,14 @@ namespace nana{	namespace drawerbase
 			{
 				API::unregister_shortkey(handle());
 
-				std::wstring wtext = ::nana::to_wstring(text);
+				native_string_type ntext = std::move(text);
 
 				wchar_t shortkey;
-				API::transform_shortkey_text(wtext, shortkey, 0);
+				API::transform_shortkey_text(to_utf8(ntext), shortkey, nullptr);
 				if (shortkey)
 					API::register_shortkey(handle(), shortkey);
 
-				base_type::_m_caption(std::move(text));
+				base_type::_m_caption(std::move(ntext));
 			}
 		//end class button
 }//end namespace nana
diff --git a/source/gui/widgets/menu.cpp b/source/gui/widgets/menu.cpp
index 065245b3..93b57240 100644
--- a/source/gui/widgets/menu.cpp
+++ b/source/gui/widgets/menu.cpp
@@ -79,7 +79,7 @@ namespace nana
 					flags.checked = false;
 				}
 
-				menu_item_type::menu_item_type(nana::string text, const event_fn_t& f)
+				menu_item_type::menu_item_type(std::string text, const event_fn_t& f)
 					: text(std::move(text)), functor(f)
 				{
 					flags.enabled = true;
@@ -148,7 +148,7 @@ namespace nana
 					img.stretch(rectangle{ img.size() }, graph, rectangle{ pos, ::nana::size(image_px, image_px) });
 				}
 
-				void item_text(graph_reference graph, const nana::point& pos, const nana::string& text, unsigned text_pixels, const attr& at)
+				void item_text(graph_reference graph, const nana::point& pos, const std::wstring& text, unsigned text_pixels, const attr& at)
 				{
 					graph.set_text_color(at.enabled ? colors::black : colors::gray_border);
 					nana::paint::text_renderer tr(graph);
@@ -240,7 +240,7 @@ namespace nana
 					return root_;
 				}
 
-				void insert(std::size_t pos, nana::string&& text, const event_fn_t& fn)
+				void insert(std::size_t pos, std::string&& text, const event_fn_t& fn)
 				{
 					if(pos < root_.items.size())
 						root_.items.emplace(root_.items.begin() + pos, std::move(text), std::ref(fn));
@@ -382,9 +382,9 @@ namespace nana
 						renderer->item(*graph_, item_r, attr);
 
 						//Draw text, the text is transformed from orignal for hotkey character
-						nana::char_t hotkey;
-						nana::string::size_type hotkey_pos;
-						nana::string text = API::transform_shortkey_text(m.text, hotkey, &hotkey_pos);
+						wchar_t hotkey;
+						std::string::size_type hotkey_pos;
+						auto text = to_wstring(API::transform_shortkey_text(m.text, hotkey, &hotkey_pos));
 
 						if (m.image.empty() == false)
 							renderer->item_image(graph, nana::point(item_r.x + 5, item_r.y + static_cast<int>(item_h_px - image_px) / 2 - 1), image_px, m.image);
@@ -1108,7 +1108,7 @@ namespace nana
 			delete impl_;
 		}
 
-		auto menu::append(const nana::string& text, const menu::event_fn_t& f) -> item_proxy
+		auto menu::append(const std::string& text, const menu::event_fn_t& f) -> item_proxy
 		{
 			impl_->mbuilder.data().items.emplace_back(text, f);
 			return item_proxy(size() - 1, impl_->mbuilder.data().items.back());
diff --git a/source/gui/widgets/menubar.cpp b/source/gui/widgets/menubar.cpp
index b7a844c2..a285afa3 100644
--- a/source/gui/widgets/menubar.cpp
+++ b/source/gui/widgets/menubar.cpp
@@ -30,11 +30,11 @@ namespace nana
 		{
 			struct item_type
 			{
-				item_type(const ::nana::string& text, unsigned long shortkey)
+				item_type(const ::std::wstring& text, unsigned long shortkey)
 					: text(text), shortkey(shortkey)
 				{}
 
-				::nana::string	text;
+				::std::wstring	text;
 				unsigned long	shortkey;
 				::nana::menu	menu_obj;
 				::nana::point	pos;
@@ -52,7 +52,7 @@ namespace nana
 						delete i;
 				}
 
-				void append(const ::nana::string& text, unsigned long shortkey)
+				void append(const ::std::wstring& text, unsigned long shortkey)
 				{
 					if(shortkey && shortkey < 0x61) shortkey += (0x61 - 0x41);
 					cont_.push_back(new item_type(text, shortkey));
@@ -122,7 +122,7 @@ namespace nana
 					graph_.rectangle(r.pare_off(1), true, body);
 				}
 
-				void item_renderer::caption(const point& pos, const nana::string& text)
+				void item_renderer::caption(const point& pos, const std::wstring& text)
 				{
 					graph_.string(pos, text, colors::black);
 				}
@@ -138,10 +138,10 @@ namespace nana
 					delete items_;
 				}
 
-				nana::menu* trigger::push_back(const ::nana::string& text)
+				nana::menu* trigger::push_back(const ::std::wstring& text)
 				{
-					::nana::char_t shkey;
-					API::transform_shortkey_text(text, shkey, nullptr);
+					wchar_t shkey;
+					API::transform_shortkey_text(to_utf8(text), shkey, nullptr);
 
 					if(shkey)
 						API::register_shortkey(widget_->handle(), shkey);
@@ -187,9 +187,9 @@ namespace nana
 					for (auto i : items_->cont())
 					{
 						//Transform the text if it contains the hotkey character
-						::nana::char_t hotkey;
-						::nana::string::size_type hotkey_pos;
-						auto text = API::transform_shortkey_text(i->text, hotkey, &hotkey_pos);
+						wchar_t hotkey;
+						::std::wstring::size_type hotkey_pos;
+						auto text = API::transform_shortkey_text(to_utf8(i->text), hotkey, &hotkey_pos);
 
 						nana::size text_s = graph.text_extent_size(text);
 
@@ -212,11 +212,11 @@ namespace nana
 
 						//Draw text, the text is transformed from orignal for hotkey character
 						int text_top_off = (item_s.height - text_s.height) / 2;
-						ird.caption({ item_pos.x + 8, item_pos.y + text_top_off }, text);
+						ird.caption({ item_pos.x + 8, item_pos.y + text_top_off }, to_wstring(text));
 
 						if (hotkey)
 						{
-							unsigned off_w = (hotkey_pos ? graph.text_extent_size(text, static_cast<unsigned>(hotkey_pos)).width : 0);
+							unsigned off_w = (hotkey_pos ? graph.text_extent_size(text.c_str(), static_cast<unsigned>(hotkey_pos)).width : 0);
 							nana::size hotkey_size = graph.text_extent_size(text.c_str() + hotkey_pos, 1);
 
 							unsigned ascent, descent, inleading;
@@ -617,9 +617,9 @@ namespace nana
 			});
 		}
 
-		menu& menubar::push_back(const nana::string& text)
+		menu& menubar::push_back(const std::string& text)
 		{
-			return *(get_drawer_trigger().push_back(text));
+			return *(get_drawer_trigger().push_back(to_wstring(text)));
 		}
 
 		menu& menubar::at(std::size_t index) const
diff --git a/source/gui/widgets/tabbar.cpp b/source/gui/widgets/tabbar.cpp
index f07e4f23..c2f5afe5 100644
--- a/source/gui/widgets/tabbar.cpp
+++ b/source/gui/widgets/tabbar.cpp
@@ -1,6 +1,6 @@
 /*
  *	A Tabbar Implementation
- *	Copyright(C) 2003-2013 Jinhao(cnjinhao@hotmail.com)
+ *	Copyright(C) 2003-2015 Jinhao(cnjinhao@hotmail.com)
  *
  *	Distributed under the Boost Software License, Version 1.0.
  *	(See accompanying file LICENSE_1_0.txt or copy at
@@ -788,7 +788,7 @@ namespace nana
 					};
 
 					for(auto & m : list_)
-						menulister_.append(m.text, fn);
+						menulister_.append(to_utf8(m.text), fn);
 
 					auto r = toolbox_.area(toolbox_.ButtonList, basis_.graph->height());
 					r.x += _m_toolbox_pos();
@@ -1006,8 +1006,10 @@ namespace nana
 								nana::size ts = basis_.graph->text_extent_size(item.text);
 								basis_.graph->set_text_color(m.fgcolor.invisible() ? fgcolor : m.fgcolor);
 								nana::paint::text_renderer tr(*basis_.graph);
+
+								std::wstring wtext = to_wstring(item.text);
 								tr.render({ m.r.x + 24, m.r.y + static_cast<int>(m.r.height - ts.height) / 2 },
-											item.text.c_str(), item.text.length(), basis_.item_pixels - 24 - 18, true);
+											wtext.c_str(), wtext.length(), basis_.item_pixels - 24 - 18, true);
 							}
 						}
 
diff --git a/source/gui/widgets/treebox.cpp b/source/gui/widgets/treebox.cpp
index 704d39c6..6c053df2 100644
--- a/source/gui/widgets/treebox.cpp
+++ b/source/gui/widgets/treebox.cpp
@@ -639,7 +639,7 @@ namespace nana
 
 				nana::paint::image* image(const node_type* node)
 				{
-					const nana::string& idstr = node->value.second.img_idstr;
+					const std::string& idstr = node->value.second.img_idstr;
 					if(idstr.size())
 					{
 						auto i = shape.image_table.find(idstr);
diff --git a/source/paint/detail/native_paint_interface.cpp b/source/paint/detail/native_paint_interface.cpp
index 77dd3c7c..110673be 100644
--- a/source/paint/detail/native_paint_interface.cpp
+++ b/source/paint/detail/native_paint_interface.cpp
@@ -1,7 +1,7 @@
 /*
  *	Platform Implementation
  *	Nana C++ Library(http://www.nanapro.org)
- *	Copyright(C) 2003-2014 Jinhao(cnjinhao@hotmail.com)
+ *	Copyright(C) 2003-2015 Jinhao(cnjinhao@hotmail.com)
  *
  *	Distributed under the Boost Software License, Version 1.0. 
  *	(See accompanying file LICENSE_1_0.txt or copy at 
@@ -129,7 +129,7 @@ namespace detail
 		pixbuf.paste(nana::rectangle(r.x, 0, r.width, r.height), dw, point{r.x, r.y});
 	}
 
-	nana::size raw_text_extent_size(drawable_type dw, const nana::char_t* text, std::size_t len)
+	nana::size raw_text_extent_size(drawable_type dw, const wchar_t* text, std::size_t len)
 	{
 		if(nullptr == dw || nullptr == text || 0 == len) return nana::size();
 #if defined(NANA_WINDOWS)
@@ -138,7 +138,7 @@ namespace detail
 			return nana::size(size.cx, size.cy);
 #elif defined(NANA_X11)
 	#if defined(NANA_UNICODE)
-		std::string utf8str = nana::charset(nana::string(text, len));
+		std::string utf8str = to_utf8(text);
 		XGlyphInfo ext;
 		XftFont * fs = reinterpret_cast<XftFont*>(dw->font->handle);
 		::XftTextExtentsUtf8(nana::detail::platform_spec::instance().open_display(), fs,
@@ -180,12 +180,6 @@ namespace detail
 #elif defined(NANA_X11)
 		auto disp = ::nana::detail::platform_spec::instance().open_display();
 	#if defined(NANA_UNICODE)
-		/*
-		std::string utf8str = nana::charset(nana::string(str, len));
-		XftFont * fs = reinterpret_cast<XftFont*>(dw->font->handle);
-		::XftDrawStringUtf8(dw->xftdraw, &(dw->xft_fgcolor), fs, pos.x, pos.y + fs->ascent,
-							reinterpret_cast<XftChar8*>(const_cast<char*>(utf8str.c_str())), utf8str.size());
-		*/
 		auto fs = reinterpret_cast<XftFont*>(dw->font->handle);
 
 		//Fixed missing array declaration by dareg
diff --git a/source/paint/graphics.cpp b/source/paint/graphics.cpp
index 53ed2e33..1227daa1 100644
--- a/source/paint/graphics.cpp
+++ b/source/paint/graphics.cpp
@@ -365,30 +365,35 @@ namespace paint
 		::nana::size graphics::text_extent_size(const ::std::string& text) const
 		{
 			throw_not_utf8(text);
-			return text_extent_size(static_cast<std::wstring>(::nana::charset(text, ::nana::unicode::utf8)));
+			return text_extent_size(to_wstring(text));
 		}
 
-		nana::size	graphics::text_extent_size(const nana::char_t* text)	const
+		::nana::size graphics::text_extent_size(const char* text, std::size_t len) const
 		{
-			return text_extent_size(text, nana::strlen(text));
+			return text_extent_size(std::string(text, text + len));
 		}
 
-		nana::size	graphics::text_extent_size(const nana::string& text)	const
+		nana::size	graphics::text_extent_size(const wchar_t* text)	const
+		{
+			return text_extent_size(text, std::wcslen(text));
+		}
+
+		nana::size	graphics::text_extent_size(const std::wstring& text)	const
 		{
 			return text_extent_size(text.c_str(), static_cast<unsigned>(text.length()));
 		}
 
-		nana::size	graphics::text_extent_size(const nana::char_t* str, std::size_t len)	const
+		nana::size	graphics::text_extent_size(const wchar_t* str, std::size_t len)	const
 		{
 			return detail::text_extent_size(handle_, str, len);
 		}
 
-		nana::size	graphics::text_extent_size(const nana::string& str, std::size_t len)	const
+		nana::size	graphics::text_extent_size(const std::wstring& str, std::size_t len)	const
 		{
 			return detail::text_extent_size(handle_, str.c_str(), len);
 		}
 
-		nana::size graphics::glyph_extent_size(const nana::char_t * str, std::size_t len, std::size_t begin, std::size_t end) const
+		nana::size graphics::glyph_extent_size(const wchar_t * str, std::size_t len, std::size_t begin, std::size_t end) const
 		{
 			if(len < end) end = len;
 			if (nullptr == handle_ || nullptr == str || 0 == len || begin >= end) return{};
@@ -414,12 +419,12 @@ namespace paint
 			return sz;
 		}
 
-		nana::size graphics::glyph_extent_size(const nana::string& str, std::size_t len, std::size_t begin, std::size_t end) const
+		nana::size graphics::glyph_extent_size(const std::wstring& str, std::size_t len, std::size_t begin, std::size_t end) const
 		{
 			return glyph_extent_size(str.c_str(), len, begin, end);
 		}
 
-		bool graphics::glyph_pixels(const nana::char_t * str, std::size_t len, unsigned* pxbuf) const
+		bool graphics::glyph_pixels(const wchar_t * str, std::size_t len, unsigned* pxbuf) const
 		{
 			if(nullptr == handle_ || nullptr == handle_->context || nullptr == str || nullptr == pxbuf) return false;
 			if(len == 0) return true;
@@ -966,12 +971,12 @@ namespace paint
 			string(pos, text_utf8);
 		}
 
-		void graphics::string(nana::point pos, const char_t* str, std::size_t len)
+		void graphics::string(nana::point pos, const wchar_t* str, std::size_t len)
 		{
 			if (handle_ && str && len)
 			{
-				const nana::char_t * end = str + len;
-				const nana::char_t * i = std::find(str, end, '\t');
+				auto const end = str + len;
+				auto i = std::find(str, end, '\t');
 #if defined(NANA_LINUX) || defined(NANA_MACOS)
 				handle_->update_text_color();
 #endif
@@ -1008,17 +1013,17 @@ namespace paint
 			}
 		}
 
-		void graphics::string(const nana::point& pos, const char_t* str)
+		void graphics::string(const nana::point& pos, const wchar_t* str)
 		{
-			string(pos, str, nana::strlen(str));
+			string(pos, str, std::wcslen(str));
 		}
 
-		void graphics::string(const nana::point& pos, const nana::string& str)
+		void graphics::string(const nana::point& pos, const std::wstring& str)
 		{
 			string(pos, str.data(), str.size());
 		}
 
-		void graphics::string(const point& pos, const ::nana::string& text, const color& clr)
+		void graphics::string(const point& pos, const ::std::wstring& text, const color& clr)
 		{
 			set_text_color(clr);
 			string(pos, text.data(), text.size());
diff --git a/source/system/platform.cpp b/source/system/platform.cpp
index 38b59398..d486f368 100644
--- a/source/system/platform.cpp
+++ b/source/system/platform.cpp
@@ -98,7 +98,7 @@ namespace system
 	}
 
 	//open an url through a default browser
-	void open_url(const nana::string& url)
+	void open_url(const std::wstring& url)
 	{
 		if(url.empty())
 			return;