diff --git a/include/nana/deploy.hpp b/include/nana/deploy.hpp
index 3765c3db..35659972 100644
--- a/include/nana/deploy.hpp
+++ b/include/nana/deploy.hpp
@@ -100,9 +100,6 @@ namespace nana
 	void throw_not_utf8(const char*, unsigned len);
 	void throw_not_utf8(const char*);
 
-	std::wstring utf8_cast(const std::string&);
-	std::string utf8_cast(const std::wstring&);
-
 	const std::string& to_utf8(const std::string&);
 	std::string to_utf8(const std::wstring&);
 
diff --git a/include/nana/filesystem/filesystem.hpp b/include/nana/filesystem/filesystem.hpp
index 4f4423a1..dc86d1e0 100644
--- a/include/nana/filesystem/filesystem.hpp
+++ b/include/nana/filesystem/filesystem.hpp
@@ -332,8 +332,6 @@ namespace filesystem
 	//uintmax_t remove_all(const path& p);
 	//uintmax_t remove_all(const path& p, error_code& ec) noexcept;
 
-	//bool rmdir(const path& p, bool fails_if_not_empty);	//deprecated
-
 	template<typename CharType>
 	std::basic_string<CharType> parent_path(const std::basic_string<CharType>& path)
 	{	
diff --git a/include/nana/gui/widgets/checkbox.hpp b/include/nana/gui/widgets/checkbox.hpp
index 4f89b422..8d458be3 100644
--- a/include/nana/gui/widgets/checkbox.hpp
+++ b/include/nana/gui/widgets/checkbox.hpp
@@ -56,14 +56,8 @@ namespace drawerbase
 			void mouse_up(graph_reference, const arg_mouse&)	override;
 		public:
 			implement * impl() const;
-		private:
-			void _m_draw_background(graph_reference);
-			void _m_draw_checkbox(graph_reference, unsigned first_line_height);
-			void _m_draw_title(graph_reference);
 		private:
 			static const int interval = 4;
-			widget* widget_;
-			std::unique_ptr<implement> imptr_;
 			implement * impl_;
 		};
 	}//end namespace checkbox
diff --git a/include/nana/gui/widgets/listbox.hpp b/include/nana/gui/widgets/listbox.hpp
index 4aa7cfb7..d8e94b0d 100644
--- a/include/nana/gui/widgets/listbox.hpp
+++ b/include/nana/gui/widgets/listbox.hpp
@@ -158,7 +158,7 @@ namespace nana
 				iresolver& operator>>(double&);
 				iresolver& operator>>(long double&);
 
-				iresolver& operator>>(std::string& utf8_cast);
+				iresolver& operator>>(std::string& text_utf8);
 				iresolver& operator>>(std::wstring&);
 				iresolver& operator>>(cell&);
 				iresolver& operator>>(std::nullptr_t);
diff --git a/source/deploy.cpp b/source/deploy.cpp
index 2594de28..3592a3bf 100644
--- a/source/deploy.cpp
+++ b/source/deploy.cpp
@@ -487,16 +487,6 @@ namespace nana
 		
 	}
 
-	std::wstring utf8_cast(const std::string& text)
-	{
-		return ::nana::charset(text, ::nana::unicode::utf8);
-	}
-
-	std::string utf8_cast(const std::wstring& text)
-	{
-		return ::nana::charset(text).to_bytes(::nana::unicode::utf8);
-	}
-
 	const std::string& to_utf8(const std::string& str)
 	{
 		return str;
diff --git a/source/detail/platform_spec_windows.cpp b/source/detail/platform_spec_windows.cpp
index de46dbea..88317ede 100644
--- a/source/detail/platform_spec_windows.cpp
+++ b/source/detail/platform_spec_windows.cpp
@@ -207,7 +207,7 @@ namespace detail
 #endif
 #endif
 		::SystemParametersInfo(SPI_GETNONCLIENTMETRICS, sizeof metrics, &metrics, 0);
-		def_font_ptr_ = make_native_font(utf8_cast(metrics.lfMessageFont.lfFaceName).c_str(), font_size_to_height(9), 400, false, false, false);
+		def_font_ptr_ = make_native_font(to_utf8(metrics.lfMessageFont.lfFaceName).c_str(), font_size_to_height(9), 400, false, false, false);
 	}
 
 	const platform_spec::font_ptr_t& platform_spec::default_native_font() const
@@ -244,7 +244,7 @@ namespace detail
 		memset(&logfont, 0, sizeof logfont);
 
 		if (name && *name)
-			std::wcscpy(logfont.lfFaceName, utf8_cast(name).c_str());
+			std::wcscpy(logfont.lfFaceName, to_wstring(name).c_str());
 		else
 			std::wcscpy(logfont.lfFaceName, def_font_ptr_->name.c_str());
 
diff --git a/source/filesystem/filesystem.cpp b/source/filesystem/filesystem.cpp
index af47ab80..59c848cf 100644
--- a/source/filesystem/filesystem.cpp
+++ b/source/filesystem/filesystem.cpp
@@ -282,20 +282,12 @@ namespace nana {	namespace experimental {
 
 		void path::_m_assign(const std::string& source_utf8)
 		{
-#if defined(NANA_WINDOWS)
-			pathstr_ = utf8_cast(source_utf8);
-#else
-			pathstr_ = source_utf8;
-#endif
+			pathstr_ = to_nstring(source_utf8);
 		}
 
 		void path::_m_assign(const std::wstring& source)
 		{
-#if defined(NANA_WINDOWS)
-			pathstr_ = source;
-#else
-			pathstr_ = utf8_cast(source);
-#endif			
+			pathstr_ = to_nstring(source);	
 		}
 		//end class path
 
diff --git a/source/gui/detail/bedrock_windows.cpp b/source/gui/detail/bedrock_windows.cpp
index 6dba26c5..0b85b644 100644
--- a/source/gui/detail/bedrock_windows.cpp
+++ b/source/gui/detail/bedrock_windows.cpp
@@ -1191,7 +1191,7 @@ namespace detail
 
 							::DragQueryFile(drop, i, varbuf.get(), reqlen);
 
-							dropfiles.files.emplace_back(utf8_cast(varbuf.get()));
+							dropfiles.files.emplace_back(to_utf8(varbuf.get()));
 						}
 
 						while(msgwnd && (msgwnd->flags.dropable == false))
diff --git a/source/gui/filebox.cpp b/source/gui/filebox.cpp
index a0985165..f89c400a 100644
--- a/source/gui/filebox.cpp
+++ b/source/gui/filebox.cpp
@@ -912,7 +912,7 @@ namespace nana
 				::GetCurrentDirectory(len, &(path[0]));
 				path.resize(len);
 
-				impl_->path = utf8_cast(path);
+				impl_->path = to_utf8(path);
 			}
 #endif
 		}
@@ -1002,9 +1002,9 @@ namespace nana
 			{
 				for(auto & f : impl_->filters)
 				{
-					filter_holder += utf8_cast(f.des);
+					filter_holder += to_wstring(f.des);
 					filter_holder += static_cast<std::wstring::value_type>('\0');
-					std::wstring fs = utf8_cast(f.type);
+					std::wstring fs = to_wstring(f.type);
 					std::size_t pos = 0;
 					while(true)
 					{
@@ -1036,8 +1036,8 @@ namespace nana
 			else
 				filter = L"All Files\0*.*\0";
 
-			auto wtitle = utf8_cast(impl_->title);
-			auto wpath = utf8_cast(impl_->path);
+			auto wtitle = to_wstring(impl_->title);
+			auto wpath = to_wstring(impl_->path);
 			ofn.lpstrFilter = filter;
 			ofn.lpstrTitle = (wtitle.empty() ? nullptr : wtitle.c_str());
 			ofn.nFilterIndex = 0;
@@ -1053,7 +1053,7 @@ namespace nana
 				return false;
 			
 			wfile.resize(std::wcslen(wfile.data()));
-			impl_->file = utf8_cast(wfile);
+			impl_->file = to_utf8(wfile);
 #elif defined(NANA_POSIX)
 			filebox_implement fb(impl_->owner, impl_->open_or_save, impl_->title);
 			
diff --git a/source/gui/msgbox.cpp b/source/gui/msgbox.cpp
index 4cd36b0f..dd20cf6e 100644
--- a/source/gui/msgbox.cpp
+++ b/source/gui/msgbox.cpp
@@ -435,7 +435,7 @@ namespace nana
         default:    break;
 		}
 
-		auto bt = ::MessageBoxW(reinterpret_cast<HWND>(API::root(wd_)), utf8_cast(sstream_.str()).c_str(), utf8_cast(title_).c_str(), type);
+		auto bt = ::MessageBoxW(reinterpret_cast<HWND>(API::root(wd_)), to_wstring(sstream_.str()).c_str(), to_wstring(title_).c_str(), type);
 
 		switch(bt)
 		{
@@ -835,7 +835,7 @@ namespace nana
 
 	void inputbox::text::tip_string(std::wstring tip)
 	{
-		impl_->tip = utf8_cast(tip);
+		impl_->tip = to_utf8(tip);
 	}
 
 	void inputbox::text::tip_string(std::string tip_utf8)
diff --git a/source/gui/place.cpp b/source/gui/place.cpp
index 0b96dbf1..d6adb5d0 100644
--- a/source/gui/place.cpp
+++ b/source/gui/place.cpp
@@ -1,7 +1,7 @@
 /*
  *	An Implementation of Place for Layout
  *	Nana C++ Library(http://www.nanapro.org)
- *	Copyright(C) 2003-2015 Jinhao(cnjinhao@hotmail.com)
+ *	Copyright(C) 2003-2016 Jinhao(cnjinhao@hotmail.com)
  *
  *	Distributed under the Boost Software License, Version 1.0.
  *	(See accompanying file LICENSE_1_0.txt or copy at
diff --git a/source/gui/place_parts.hpp b/source/gui/place_parts.hpp
index 5daba048..25708b93 100644
--- a/source/gui/place_parts.hpp
+++ b/source/gui/place_parts.hpp
@@ -83,7 +83,7 @@ namespace nana
 				graph.rectangle(true, static_cast<color_rgb>(0x83EB));
 
 				//draw caption
-				auto text = utf8_cast(API::window_caption(window_handle_));
+				auto text = to_wstring(API::window_caption(window_handle_));
 				text_rd_->render({ 3, 1 }, text.data(), text.size(), graph.size().width - 20, true);
 
 				//draw x button
diff --git a/source/gui/widgets/checkbox.cpp b/source/gui/widgets/checkbox.cpp
index e0e0aa75..31ef7146 100644
--- a/source/gui/widgets/checkbox.cpp
+++ b/source/gui/widgets/checkbox.cpp
@@ -17,39 +17,68 @@
 
 namespace nana{ namespace drawerbase
 {
-namespace checkbox
-{
-	typedef element::crook_interface::state crook_state;
-
-	struct drawer::implement
+	namespace checkbox
 	{
-		bool react;
-		bool radio;
-		facade<element::crook> crook;
-	};
+		typedef element::crook_interface::state crook_state;
+
+		struct drawer::implement
+		{
+			widget * widget_ptr;
+			bool react;
+			bool radio;
+			facade<element::crook> crook;
+		};
+
+		//class drawer
 
 			drawer::drawer()
-				: widget_(nullptr),
-					imptr_(new drawer::implement),
-					impl_(imptr_.get())
+				:	impl_(new implement)
 			{
+				impl_->widget_ptr = nullptr;
 				impl_->react = true;
 				impl_->radio = false;
 			}
 
 			drawer::~drawer()
-			{}
+			{
+				delete impl_;
+			}
 
 			void drawer::attached(widget_reference widget, graph_reference)
 			{
-				widget_ = &widget;
+				impl_->widget_ptr = &widget;
 			}
 
 			void drawer::refresh(graph_reference graph)
 			{
-				_m_draw_background(graph);
-				_m_draw_title(graph);
-				_m_draw_checkbox(graph, graph.text_extent_size(L"jN", 2).height + 2);
+				auto wdg = impl_->widget_ptr;
+
+				//draw background
+				if (bground_mode::basic != API::effects_bground_mode(*wdg))
+					graph.rectangle(true, wdg->bgcolor());
+
+				//draw title
+				if (graph.width() > 16 + interval)
+				{
+					auto title = to_wstring(wdg->caption_native());
+					unsigned pixels = graph.width() - (16 + interval);
+
+					nana::paint::text_renderer tr(graph);
+					if (!wdg->enabled())
+					{
+						graph.palette(true, colors::white);
+						tr.render({ 17 + interval, 2 }, title.c_str(), title.length(), pixels);
+						graph.palette(true, static_cast<color_rgb>(0x808080));
+					}
+					else
+						graph.palette(true, wdg->fgcolor());
+
+					tr.render({ 16 + interval, 1 }, title.c_str(), title.length(), pixels);
+				}
+
+				//draw crook
+				auto txt_px = graph.text_extent_size(L"jN", 2).height + 2;
+				impl_->crook.draw(graph, wdg->bgcolor(), wdg->fgcolor(), rectangle(0, txt_px > 16 ? (txt_px - 16) / 2 : 0, 16, 16), API::element_state(*wdg));
 			}
 
 			void drawer::mouse_down(graph_reference graph, const arg_mouse&)
@@ -63,8 +92,8 @@ namespace checkbox
 				if (impl_->react)
 				{
 					impl_->crook.reverse();
-					arg_checkbox arg{ static_cast<nana::checkbox*>(widget_) };
-					API::events<nana::checkbox>(widget_->handle()).checked.emit(arg);
+					arg_checkbox arg{ static_cast<nana::checkbox*>(impl_->widget_ptr) };
+					API::events<nana::checkbox>(impl_->widget_ptr->handle()).checked.emit(arg);
 				}
 				refresh(graph);
 				API::lazy_refresh();
@@ -86,39 +115,6 @@ namespace checkbox
 			{
 				return impl_;
 			}
-
-			void drawer::_m_draw_background(graph_reference graph)
-			{
-				if(bground_mode::basic != API::effects_bground_mode(*widget_))
-					graph.rectangle(true, API::bgcolor(*widget_));
-			}
-
-			void drawer::_m_draw_checkbox(graph_reference graph, unsigned first_line_height)
-			{
-				impl_->crook.draw(graph, widget_->bgcolor(), widget_->fgcolor(), rectangle(0, first_line_height > 16 ? (first_line_height - 16) / 2 : 0, 16, 16), API::element_state(*widget_));
-			}
-
-			void drawer::_m_draw_title(graph_reference graph)
-			{
-				if (graph.width() > 16 + interval)
-				{
-					std::wstring title = ::nana::charset(widget_->caption(), ::nana::unicode::utf8);
-
-					unsigned pixels = graph.width() - (16 + interval);
-
-					nana::paint::text_renderer tr(graph);
-					if (API::window_enabled(widget_->handle()) == false)
-					{
-						graph.palette(true, colors::white);
-						tr.render({ 17 + interval, 2 }, title.c_str(), title.length(), pixels);
-						graph.palette(true, { 0x80, 0x80, 0x80 });
-					}
-					else
-						graph.palette(true, widget_->fgcolor());
-
-					tr.render({ 16 + interval, 1 }, title.c_str(), title.length(), pixels);
-				}
-			}
 		//end class drawer
 	} //end namespace checkbox
 }//end namespace drawerbase
@@ -209,6 +205,7 @@ namespace checkbox
 				e.uiobj->react(true);
 				API::umake_event(e.eh_checked);
 				API::umake_event(e.eh_destroy);
+				API::umake_event(e.eh_keyboard);
 			}
 		}
 
diff --git a/source/gui/widgets/label.cpp b/source/gui/widgets/label.cpp
index c6f0ca1f..ed6c2828 100644
--- a/source/gui/widgets/label.cpp
+++ b/source/gui/widgets/label.cpp
@@ -851,7 +851,7 @@ namespace nana
 			throw_not_utf8(str);
 			drawerbase::label::renderer rd;
 			rd.format(format_enabled);
-			rd.parse(utf8_cast(str));
+			rd.parse(to_wstring(str));
 			return rd.measure(graph, allowed_width_in_pixel, h_align, v_align);
 		}
 
diff --git a/source/gui/widgets/skeletons/text_editor.cpp b/source/gui/widgets/skeletons/text_editor.cpp
index 34e85650..fc6086cc 100644
--- a/source/gui/widgets/skeletons/text_editor.cpp
+++ b/source/gui/widgets/skeletons/text_editor.cpp
@@ -1,7 +1,7 @@
 /*
  *	A text editor implementation
  *	Nana C++ Library(http://www.nanapro.org)
- *	Copyright(C) 2003-2015 Jinhao(cnjinhao@hotmail.com)
+ *	Copyright(C) 2003-2016 Jinhao(cnjinhao@hotmail.com)
  *
  *	Distributed under the Boost Software License, Version 1.0.
  *	(See accompanying file LICENSE_1_0.txt or copy at
@@ -1255,11 +1255,12 @@ namespace nana{	namespace widgets
 						return (a.begin < b.begin);
 					});
 
-					auto previous = entities.begin();
-					auto i = previous + 1;
-					while(i != entities.end())
+					auto i = entities.begin();
+					auto bound = i->end;
+
+					for (++i; i != entities.end(); )
 					{
-						if (previous->end > i->begin)
+						if (bound > i->begin)
 							i = entities.erase(i);  // erase overlaping. Left only the first.
 						else
 							++i;
@@ -1321,7 +1322,7 @@ namespace nana{	namespace widgets
 			auto sp = std::make_shared<keyword_scheme>();
 			sp->fgcolor = fgcolor;
 			sp->bgcolor = bgcolor;
-			keywords_->schemes[name] = sp;
+			keywords_->schemes[name].swap(sp);
 		}
 
 		void text_editor::erase_highlight(const std::string& name)
diff --git a/source/gui/widgets/textbox.cpp b/source/gui/widgets/textbox.cpp
index 95dacd30..6c69b362 100644
--- a/source/gui/widgets/textbox.cpp
+++ b/source/gui/widgets/textbox.cpp
@@ -319,7 +319,7 @@ namespace drawerbase {
 				std::wstring line_text;
 				if (editor->getline(line_index, line_text))
 				{
-					text = utf8_cast(line_text);
+					text = to_utf8(line_text);
 					return true;
 				}
 			}
diff --git a/source/gui/widgets/treebox.cpp b/source/gui/widgets/treebox.cpp
index 6c053df2..73913ba3 100644
--- a/source/gui/widgets/treebox.cpp
+++ b/source/gui/widgets/treebox.cpp
@@ -343,8 +343,8 @@ namespace nana
 					else
 					{
 						wchar_t wstr[2] = { key, 0 };
-						pattern += utf8_cast(wstr);
-						track_node.key_buf += utf8_cast(wstr);
+						pattern += to_utf8(wstr);
+						track_node.key_buf += to_utf8(wstr);
 					}
 
 					const node_type *begin = node_state.selected ? node_state.selected : attr.tree_cont.get_root()->child;
@@ -995,7 +995,7 @@ namespace nana
 
 				bool item_proxy::operator==(const wchar_t* s) const
 				{
-					return (node_ && s && (node_->value.second.text == utf8_cast(s)));
+					return (node_ && s && (node_->value.second.text == to_utf8(s)));
 				}
 
 				// Behavior of Iterator
diff --git a/source/paint/graphics.cpp b/source/paint/graphics.cpp
index 65d537c7..3a84ca17 100644
--- a/source/paint/graphics.cpp
+++ b/source/paint/graphics.cpp
@@ -949,8 +949,7 @@ namespace paint
 
 		void graphics::string(const point& pos, const std::string& text_utf8)
 		{
-			throw_not_utf8(text_utf8);
-			string(pos, utf8_cast(text_utf8));
+			string(pos, to_wstring(text_utf8));
 		}
 
 		void graphics::string(const point& pos, const std::string& text_utf8, const color& clr)
diff --git a/source/system/dataexch.cpp b/source/system/dataexch.cpp
index cf18c153..992a76d3 100644
--- a/source/system/dataexch.cpp
+++ b/source/system/dataexch.cpp
@@ -43,7 +43,7 @@ namespace nana{ namespace system{
 #ifdef NANA_WINDOWS
 			_m_set(format::text, text.c_str(), (text.length() + 1) * sizeof(wchar_t));
 #else
-			std::string str = utf8_cast(text);
+			std::string str = to_utf8(text);
 			_m_set(format::text, str.c_str(), str.size() + 1);
 #endif
 		}
@@ -129,7 +129,7 @@ namespace nana{ namespace system{
 				if (pos != wstr.npos)
 					wstr.erase(pos + 1);
 
-				text_utf8 = utf8_cast(wstr);
+				text_utf8 = to_utf8(wstr);
 #else
 				text_utf8.reserve(size);
 				text_utf8.append(reinterpret_cast<char*>(res), reinterpret_cast<char*>(res) + size);
@@ -169,7 +169,7 @@ namespace nana{ namespace system{
 					text_utf8.erase(pos + 1);
 				::XFree(res);
 
-				str = utf8_cast(text_utf8);
+				str = to_wstring(text_utf8);
 #endif
 			}
 		}