diff --git a/.travis.yml b/.travis.yml
index c5ff05f4..ed1b44de 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -56,7 +56,7 @@ matrix:
             - llvm-toolchain-precise 
 
 before_install:
-  - git clone --depth=1 --branch=dev_nana_in_examples https://github.com/qPCR4vir/nana-demo.git nana-demo
+  - git clone --depth=1 --branch=dev_nana_fs https://github.com/qPCR4vir/nana-demo.git nana-demo
   - export PATH="$HOME/bin:$PATH"
   - mkdir ~/bin
   - wget --no-check-certificate --no-clobber -O /tmp/tools/cmake https://cmake.org/files/v3.4/cmake-3.4.0-rc3-Linux-x86_64.sh || true
diff --git a/include/nana/c++defines.hpp b/include/nana/c++defines.hpp
index 071f984f..29cb0e0f 100644
--- a/include/nana/c++defines.hpp
+++ b/include/nana/c++defines.hpp
@@ -59,6 +59,7 @@
 
 #		define constexpr const	//no support of constexpr until Visual C++ 2015 ? const ??
 #	endif
+#	undef STD_FILESYSTEM_NOT_SUPPORTED
 #elif defined(__GNUC__)
 #	if (__GNUC__ == 4 && __GNUC_MINOR__ < 6)
 #		define noexcept		//no support of noexcept until GCC 4.6
diff --git a/include/nana/filesystem/filesystem.hpp b/include/nana/filesystem/filesystem.hpp
index a62a5707..1a447abf 100644
--- a/include/nana/filesystem/filesystem.hpp
+++ b/include/nana/filesystem/filesystem.hpp
@@ -30,6 +30,9 @@
 #ifndef NANA_FILESYSTEM_HPP
 #define NANA_FILESYSTEM_HPP
 
+//#undef  NANA_USING_NANA_FILESYSTEM 
+#if NANA_USING_NANA_FILESYSTEM 
+
 #include <nana/push_ignore_diagnostic>
 
 #include <string>
@@ -233,18 +236,18 @@ namespace nana  { namespace experimental { namespace filesystem
 	{
 	public:
 		directory_entry() = default;
-		explicit directory_entry(const path&);
+		explicit directory_entry(const ::nana::experimental::filesystem::path&);
 
 		//modifiers
-		void assign(const path&);
-		void replace_filename(const path&);
+		void assign(const ::nana::experimental::filesystem::path&);
+		void replace_filename(const ::nana::experimental::filesystem::path&);
 
 		//observers
 		file_status status() const;
-		operator const filesystem::path&() const;
+		operator const filesystem::path&() const {	return path_;	};
 		const filesystem::path& path() const;
 	private:
-		filesystem::path path_;
+		::nana::experimental::filesystem::path path_;
 	};
 
     /// InputIterator that iterate over the sequence of directory_entry elements representing the files in a directory, not an recursive_directory_iterator
@@ -356,7 +359,6 @@ namespace nana  { namespace experimental { namespace filesystem
 	bool create_directory(const path& p, const path& attributes);
 	//bool create_directory(const path& p, const path& attributes,     error_code& ec) noexcept;
 	
-	bool modified_file_time(const path& p, struct tm&);    ///< extention ?
 
 	/// The time of last data modification of p, determined as if by the value of the POSIX
     /// stat structure member st_mtime obtained as if by POSIX stat().
@@ -364,7 +366,6 @@ namespace nana  { namespace experimental { namespace filesystem
 	/// returns file_time_type::min() if an error occurs
 	//file_time_type last_write_time(const path& p, error_code& ec) noexcept;
 
-	path path_user();    ///< extention ?
 
 	path current_path();
 	//path current_path(error_code& ec);
@@ -414,3 +415,4 @@ namespace nana  { namespace experimental { namespace filesystem
 
 #include <nana/pop_ignore_diagnostic>
 #endif
+#endif
diff --git a/include/nana/filesystem/filesystem_ext.hpp b/include/nana/filesystem/filesystem_ext.hpp
index feb68fa9..115c3dd1 100644
--- a/include/nana/filesystem/filesystem_ext.hpp
+++ b/include/nana/filesystem/filesystem_ext.hpp
@@ -15,10 +15,16 @@
 #ifndef NANA_FILESYSTEM_EXT_HPP
 #define NANA_FILESYSTEM_EXT_HPP
 
+#include <sstream>
 #include <iomanip>
+
 #include <nana/filesystem/filesystem_selector.hpp>
 
-namespace nana {namespace experimental {namespace filesystem {namespace ext {
+namespace nana 
+{
+namespace filesystem_ext 
+{
+
 #if defined(NANA_WINDOWS)
     constexpr auto def_root = "C:";
     constexpr auto def_rootstr = "C:\\";
@@ -28,15 +34,14 @@ namespace nana {namespace experimental {namespace filesystem {namespace ext {
     constexpr auto def_rootstr = "/";
     constexpr auto def_rootname = "Root/";
 #endif
-
-// nana::experimental::filesystem::path_user());    
+ 
+std::experimental::filesystem::path path_user();    ///< extention ?
 
 inline bool is_directory(const std::experimental::filesystem::directory_entry& dir) noexcept
 {
     return is_directory(dir.status());
 }
 
-
 //template<class DI> // DI = directory_iterator from std, boost, or nana : return directory_entry
 class directory_only_iterator : public std::experimental::filesystem::directory_iterator
 { 
@@ -78,7 +83,6 @@ inline directory_only_iterator end(const directory_only_iterator&) noexcept
 	return{};
 }
 
-
 //template<class DI> // DI = directory_iterator from std, boost, or nana : value_type directory_entry
 class regular_file_only_iterator : public std::experimental::filesystem::directory_iterator
 {
@@ -115,53 +119,13 @@ inline regular_file_only_iterator end(const regular_file_only_iterator&) noexcep
 	return{};
 }
 
-inline std::string pretty_file_size(const std::experimental::filesystem::path& path) // todo: move to .cpp
-{
-    try {
-        auto bytes = std::experimental::filesystem::file_size ( path );
-        const char * ustr[] = { " KB", " MB", " GB", " TB" };
-        std::stringstream ss;
-        if (bytes < 1024)
-            ss << bytes << " Bytes";
-        else
-        {
-            double cap = bytes / 1024.0;
-            std::size_t uid = 0;
-            while ((cap >= 1024.0) && (uid < sizeof(ustr) / sizeof(char *)))
-            {
-                cap /= 1024.0;
-                ++uid;
-            }
-            ss << cap;
-            auto s = ss.str();
-            auto pos = s.find('.');
-            if (pos != s.npos)
-            {
-                if (pos + 2 < s.size())
-                    s.erase(pos + 2);
-            }
-            return s + ustr[uid];
-        }
+std::string pretty_file_size(const std::experimental::filesystem::path& path);
 
-        return ss.str();
-    }
-    catch (...) {}
-    return {};
-}
+std::string pretty_file_date(const std::experimental::filesystem::path& path);
 
-inline std::string pretty_file_date(const std::experimental::filesystem::path& path) // todo: move to .cpp
-{
-    try {
-        auto ftime = std::experimental::filesystem::last_write_time(path);
-        std::time_t cftime = decltype(ftime)::clock::to_time_t(ftime);
-        std::stringstream tm;
-        tm << std::put_time(std::localtime(&cftime), "%Y-%m-%d, %H:%M:%S");
-        return tm.str();
-    }
-    catch (...) {
-        return {};
-    }
-}
+bool modified_file_time(const std::experimental::filesystem::path& p, struct tm&);    ///< extention ?
+
+}  // filesystem_ext
+}  // nana
 
-}}}}
 #endif //NANA_FILESYSTEM_EXT_HPP
diff --git a/include/nana/filesystem/filesystem_selector.hpp b/include/nana/filesystem/filesystem_selector.hpp
index 5ccfabc5..0d9c78dd 100644
--- a/include/nana/filesystem/filesystem_selector.hpp
+++ b/include/nana/filesystem/filesystem_selector.hpp
@@ -35,6 +35,8 @@
 
 #if (defined(NANA_FILESYSTEM_FORCE) || ( (defined(STD_FILESYSTEM_NOT_SUPPORTED) && !defined(BOOST_FILESYSTEM_AVAILABLE)) && !(defined(BOOST_FILESYSTEM_FORCE) || defined(STD_FILESYSTEM_FORCE)) ) )
 
+#undef  NANA_USING_NANA_FILESYSTEM 
+#define NANA_USING_NANA_FILESYSTEM  true		
 #   include <nana/filesystem/filesystem.hpp>
 
 namespace std {
@@ -46,14 +48,14 @@ namespace std {
 #       else
 			using namespace nana::experimental::filesystem::v1;
 #       endif
-#undef  NANA_USING_NANA_FILESYSTEM 
-#define NANA_USING_NANA_FILESYSTEM  true		
 		} // filesystem
 	} // experimental
 } // std
 
 #elif (defined(BOOST_FILESYSTEM_AVAILABLE) && ( defined(BOOST_FILESYSTEM_FORCE) || ( defined(STD_FILESYSTEM_NOT_SUPPORTED) && !defined(STD_FILESYSTEM_FORCE) ) )) 
 
+#undef  NANA_USING_BOOST_FILESYSTEM
+#define NANA_USING_BOOST_FILESYSTEM true
 #   include <boost/filesystem.hpp>
 
 	// add boost::filesystem into std::experimental::filesystem
@@ -61,17 +63,15 @@ namespace std {
 	namespace experimental {
 		namespace filesystem {
                   using namespace boost::filesystem;
-#undef  NANA_USING_BOOST_FILESYSTEM
-#define NANA_USING_BOOST_FILESYSTEM true
 		} // filesystem
 	} // experimental
 } // std
 
 #else
 
-#    include <experimental/filesystem>
 #undef NANA_USING_STD_FILESYSTEM 
 #define NANA_USING_STD_FILESYSTEM true
+#    include <experimental/filesystem>
 #endif
 
 #ifndef __cpp_lib_experimental_filesystem
diff --git a/include/nana/gui/filebox.hpp b/include/nana/gui/filebox.hpp
index 3a9b9f4c..561dc5b7 100644
--- a/include/nana/gui/filebox.hpp
+++ b/include/nana/gui/filebox.hpp
@@ -1,4 +1,4 @@
-/*
+/**
  *	Filebox
  *	Nana C++ Library(http://www.nanapro.org)
  *	Copyright(C) 2003-2016 Jinhao(cnjinhao@hotmail.com)
@@ -7,7 +7,9 @@
  *	(See accompanying file LICENSE_1_0.txt or copy at
  *	http://www.boost.org/LICENSE_1_0.txt)
  *
- *	@file: nana/gui/filebox.hpp
+ *	@file nana/gui/filebox.hpp
+ *  @author Jinhao
+ *  @brief a dialog to chose file(s), implemented "native" in windows but using nana for X11 
  */
 
 #ifndef NANA_GUI_FILEBOX_HPP
@@ -37,18 +39,20 @@ namespace nana
 		/// Change owner window
 		void owner(window);
 
-		/// specify a title for the dialog
+		/// Set a new title for the dialog
 		/// @param	string	a text for title
-		/// @return old title.
-		::std::string title( ::std::string new_title); ///< . Set a new title for the dialog and \return the old title
+		/// @return the old title.
+		::std::string title( ::std::string new_title);  
 
-		/**	@brief	specify a suggestion directory
-		 *	@param	string	a path of initial directory
+		/**	@brief	Suggest initial path used to locate a directory when the filebox starts.
+		 *	@param	string	initial_directory a path of initial directory
 		 *	@note	the behavior of init_path is different between Win7 and Win2K/XP/Vista, but its behavior under Linux is conformed with Win7.
 		 */
-		filebox& init_path(const ::std::string&); ///< Suggested init path used to locate a directory when the filebox starts.
+		filebox& init_path(const ::std::string& initial_directory);
+
 		filebox& init_file(const ::std::string&); ///< Init file, if it contains a path, the init path is replaced by the path of init file.
-        /// \brief Add a filetype filter. 
+        
+		/// \brief Add a filetype filter. 
         /// To specify multiple filter in a single description, use a semicolon to separate the patterns(for example,"*.TXT;*.DOC;*.BAK").
 		filebox& add_filter(const ::std::string& description,  ///< for example. "Text File"
                             const ::std::string& filetype      ///< filter pattern(for example, "*.TXT")
@@ -68,8 +72,7 @@ namespace nana
 		/// Display the filebox dialog
 		bool show() const;
 		
-		/// Display the filebox dialog
-		/// A function object method alternative to show()
+		/// a function object method alternative to show() to display the filebox dialog, 
 		bool operator()() const
 		{
 			return show();
diff --git a/include/nana/paint/detail/image_impl_interface.hpp b/include/nana/paint/detail/image_impl_interface.hpp
index 4a0a1722..3e75d18e 100644
--- a/include/nana/paint/detail/image_impl_interface.hpp
+++ b/include/nana/paint/detail/image_impl_interface.hpp
@@ -2,7 +2,7 @@
 #define NANA_PAINT_DETAIL_IMAGE_IMPL_INTERFACE_HPP
 
 #include "../image.hpp"
-#include <nana/filesystem/filesystem.hpp>
+#include <nana/filesystem/filesystem_ext.hpp>
 
 namespace nana{	namespace paint{
 
@@ -16,7 +16,7 @@ namespace nana{	namespace paint{
 	public:
 		typedef nana::paint::graphics& graph_reference;
 		virtual ~image_impl_interface() = 0;	//The destructor is defined in ../image.cpp
-		virtual bool open(const nana::experimental::filesystem::path& file) = 0;
+		virtual bool open(const std::experimental::filesystem::path& file) = 0;
 		virtual bool open(const void* data, std::size_t bytes) = 0; // reads image from memory
 		virtual bool alpha_channel() const = 0;
 		virtual bool empty() const = 0;
diff --git a/include/nana/paint/graphics.hpp b/include/nana/paint/graphics.hpp
index fec075ab..7102c500 100644
--- a/include/nana/paint/graphics.hpp
+++ b/include/nana/paint/graphics.hpp
@@ -13,10 +13,11 @@
 #ifndef NANA_PAINT_GRAPHICS_HPP
 #define NANA_PAINT_GRAPHICS_HPP
 
+#include <memory>
+
 #include "../basic_types.hpp"
 #include "../gui/basis.hpp"
 #include "pixel_buffer.hpp"
-#include <memory>
 
 namespace nana
 {
diff --git a/source/filesystem/filesystem.cpp b/source/filesystem/filesystem.cpp
index 69f467cf..8a810f3a 100644
--- a/source/filesystem/filesystem.cpp
+++ b/source/filesystem/filesystem.cpp
@@ -11,7 +11,7 @@
  *		provide some interface for file managment
  */
 
-#include <nana/filesystem/filesystem.hpp>
+#include <nana/filesystem/filesystem_ext.hpp>
 #include <vector>
 #if defined(NANA_WINDOWS)
     #include <windows.h>
@@ -36,6 +36,121 @@
 	#include <stdlib.h>
 #endif
 
+namespace fs = std::experimental::filesystem;
+
+namespace nana
+{
+	namespace filesystem_ext
+	{
+
+		fs::path path_user()
+		{
+#if defined(NANA_WINDOWS)
+			wchar_t pstr[MAX_PATH];
+			if (SUCCEEDED(SHGetFolderPath(0, CSIDL_PROFILE, 0, SHGFP_TYPE_CURRENT, pstr)))
+				return pstr;
+#elif defined(NANA_LINUX) || defined(NANA_MACOS)
+			const char * pstr = ::getenv("HOME");
+			if (pstr)
+				return pstr;
+#endif
+			return fs::path();
+		}
+
+		std::string pretty_file_size(const fs::path& path)  
+		{
+			try {
+				auto bytes = fs::file_size(path);
+				const char * ustr[] = { " KB", " MB", " GB", " TB" };
+				std::stringstream ss;
+				if (bytes < 1024)
+					ss << bytes << " Bytes";
+				else
+				{
+					double cap = bytes / 1024.0;
+					std::size_t uid = 0;
+					while ((cap >= 1024.0) && (uid < sizeof(ustr) / sizeof(char *)))
+					{
+						cap /= 1024.0;
+						++uid;
+					}
+					ss << cap;
+					auto s = ss.str();
+					auto pos = s.find('.');
+					if (pos != s.npos)
+					{
+						if (pos + 2 < s.size())
+							s.erase(pos + 2);
+					}
+					return s + ustr[uid];
+				}
+
+				return ss.str();
+			}
+			catch (...) {}
+			return{};
+		}
+
+		std::string pretty_file_date(const fs::path& path) // todo: move to .cpp
+		{
+			try {
+				auto ftime = fs::last_write_time(path);
+
+				// crash: VS2015 will not read the time for some files (for example: C:/hiberfil.sys)
+				//   and will return file_time_type(-1) without throwing
+				//   https://msdn.microsoft.com/en-us/library/dn823784.aspx
+
+				if (ftime == ((fs::file_time_type::min)())) return{};
+
+				std::time_t cftime = decltype(ftime)::clock::to_time_t(ftime);
+				std::stringstream tm;
+				tm << std::put_time(std::localtime(&cftime), "%Y-%m-%d, %H:%M:%S");
+				return tm.str();
+			}
+			catch (...) {
+				return{};
+			}
+		}
+
+		bool modified_file_time(const fs::path& p, struct tm& t)
+		{
+#if defined(NANA_WINDOWS)
+			WIN32_FILE_ATTRIBUTE_DATA attr;
+			if (::GetFileAttributesEx(p.c_str(), GetFileExInfoStandard, &attr))
+			{
+				FILETIME local_file_time;
+				if (::FileTimeToLocalFileTime(&attr.ftLastWriteTime, &local_file_time))
+				{
+					SYSTEMTIME st;
+					::FileTimeToSystemTime(&local_file_time, &st);
+					t.tm_year = st.wYear - 1900;
+					t.tm_mon = st.wMonth - 1;
+					t.tm_mday = st.wDay;
+					t.tm_wday = st.wDayOfWeek - 1;
+					t.tm_yday = nana::date::day_in_year(st.wYear, st.wMonth, st.wDay);
+
+					t.tm_hour = st.wHour;
+					t.tm_min = st.wMinute;
+					t.tm_sec = st.wSecond;
+					return true;
+				}
+			}
+#elif defined(NANA_POSIX)
+			struct stat attr;
+			if (0 == ::stat(p.c_str(), &attr))
+			{
+				t = *(::localtime(&attr.st_ctime));
+				return true;
+			}
+#endif
+			return false;
+		}
+	}
+}
+
+#if NANA_USING_NANA_FILESYSTEM 
+
+namespace nana_fs = nana::experimental::filesystem;
 
 namespace nana {	namespace experimental {	namespace filesystem
 	{
@@ -143,7 +258,7 @@ namespace nana {	namespace experimental {	namespace filesystem
 
 		path path::parent_path() const
 		{
-			return{filesystem::parent_path(pathstr_)};
+			return{nana_fs::parent_path(pathstr_)};
 		}
 
 		file_type path::what() const
@@ -342,17 +457,17 @@ namespace nana {	namespace experimental {	namespace filesystem
 		}
 
 		//class directory_entry
-			directory_entry::directory_entry(const filesystem::path& p)
+			directory_entry::directory_entry(const nana_fs::path& p)
 				:path_{ p }
 			{}
 
 			//modifiers
-			void directory_entry::assign(const  filesystem::path& p)
+			void directory_entry::assign(const  nana_fs::path& p)
 			{
 				path_ = p;
 			}
 
-			void directory_entry::replace_filename(const  filesystem::path& p)
+			void directory_entry::replace_filename(const  nana_fs::path& p)
 			{
 				path_ = path_.parent_path() / p;
 			}
@@ -360,15 +475,15 @@ namespace nana {	namespace experimental {	namespace filesystem
 			//observers
 			file_status directory_entry::status() const
 			{
-				return filesystem::status(path_);
+				return nana_fs::status(path_);
 			}
 
-			directory_entry::operator const filesystem::path&() const
-			{
-				return path_;
-			}
+			//directory_entry::operator const nana_fs::path&() const
+			//{
+			//	return path_;
+			//}
 
-			const path& directory_entry::path() const
+			const nana_fs::path& directory_entry::path() const
 			{
 				return path_;
 			}
@@ -751,44 +866,11 @@ namespace nana {	namespace experimental {	namespace filesystem
 #endif
 		}
 
-		bool modified_file_time(const path& p, struct tm& t)
-		{
-#if defined(NANA_WINDOWS)
-			WIN32_FILE_ATTRIBUTE_DATA attr;
-			if (::GetFileAttributesEx(p.c_str(), GetFileExInfoStandard, &attr))
-			{
-				FILETIME local_file_time;
-				if (::FileTimeToLocalFileTime(&attr.ftLastWriteTime, &local_file_time))
-				{
-					SYSTEMTIME st;
-					::FileTimeToSystemTime(&local_file_time, &st);
-					t.tm_year = st.wYear - 1900;
-					t.tm_mon = st.wMonth - 1;
-					t.tm_mday = st.wDay;
-					t.tm_wday = st.wDayOfWeek - 1;
-					t.tm_yday = nana::date::day_in_year(st.wYear, st.wMonth, st.wDay);
-
-					t.tm_hour = st.wHour;
-					t.tm_min = st.wMinute;
-					t.tm_sec = st.wSecond;
-					return true;
-				}
-			}
-#elif defined(NANA_POSIX)
-			struct stat attr;
-			if (0 == ::stat(p.c_str(), &attr))
-			{
-				t = *(::localtime(&attr.st_ctime));
-				return true;
-			}
-#endif
-			return false;
-		}
 
 		file_time_type last_write_time(const path& p)
 		{
 			struct tm t;
-			modified_file_time(p, t);   
+			nana::filesystem_ext::modified_file_time(p, t);   
 			std::chrono::system_clock::time_point dateTime =std::chrono::system_clock::from_time_t( mktime(&t) );
 			return 	dateTime;
 		}
@@ -821,20 +903,6 @@ namespace nana {	namespace experimental {	namespace filesystem
 				return detail::rm_file(p);
 			}
 
-			path path_user()
-			{
-#if defined(NANA_WINDOWS)
-				wchar_t pstr[MAX_PATH];
-				if (SUCCEEDED(SHGetFolderPath(0, CSIDL_PROFILE, 0, SHGFP_TYPE_CURRENT, pstr)))
-					return pstr;
-#elif defined(NANA_LINUX) || defined(NANA_MACOS)
-				const char * pstr = ::getenv("HOME");
-				if (pstr)
-					return pstr;
-#endif
-				return path();
-			}
-
 			path current_path()
 			{
 #if defined(NANA_WINDOWS)
@@ -887,3 +955,5 @@ namespace nana {	namespace experimental {	namespace filesystem
 		}//end namespace filesystem
 	} //end namespace experimental
 }//end namespace nana
+#endif
+
diff --git a/source/gui/filebox.cpp b/source/gui/filebox.cpp
index 5f8f1311..c18c7a83 100644
--- a/source/gui/filebox.cpp
+++ b/source/gui/filebox.cpp
@@ -12,7 +12,7 @@
 
 #include <nana/gui.hpp>
 #include <nana/gui/filebox.hpp>
-#include <nana/filesystem/filesystem.hpp>
+#include <nana/filesystem/filesystem_ext.hpp>
 
 #if defined(NANA_WINDOWS)
 	#include <windows.h>
@@ -24,12 +24,15 @@
 	#include <nana/gui/widgets/textbox.hpp>
 	#include <nana/gui/widgets/treebox.hpp>
 	#include <nana/gui/widgets/combox.hpp>
-	#include <nana/filesystem/filesystem.hpp>
 	#include <nana/gui/place.hpp>
 	#include <stdexcept>
 	#include <algorithm>
 #endif
 
+namespace fs = std::experimental::filesystem;
+namespace fs_ext = nana::filesystem_ext;
+
+
 namespace nana
 {
 #if defined(NANA_POSIX)
@@ -54,7 +57,7 @@ namespace nana
 			friend listbox::oresolver& operator<<(listbox::oresolver& ores, const item_fs& item)
 			{
 				std::wstringstream tm;
-				tm<<(item.modified_time.tm_year + 1900)<<'-';
+				tm<<(item.modified_time.tm_year + 1900)<<'-';    /// \todo : use nana::filesystem_ext:: pretty_file_date
 				_m_add(tm, item.modified_time.tm_mon + 1)<<'-';
 				_m_add(tm, item.modified_time.tm_mday)<<' ';
 
@@ -87,7 +90,7 @@ namespace nana
 				return ss;
 			}
 
-			static std::string _m_trans(std::size_t bytes)
+			static std::string _m_trans(std::size_t bytes)  /// \todo : use nana::filesystem_ext::pretty_file_size
 			{
 				const char * ustr[] = {" KB", " MB", " GB", " TB"};
 				std::stringstream ss;
@@ -142,13 +145,13 @@ namespace nana
 				auto path = path_.caption();
 				auto root = path.substr(0, path.find('/'));
 				if(root == "HOME")
-					path.replace(0, 4, nana::experimental::filesystem::path_user().native());
+					path.replace(0, 4, fs_ext::path_user().native());
 				else if(root == "FILESYSTEM")
 					path.erase(0, 10);
 				else
 					throw std::runtime_error("Nana.GUI.Filebox: Wrong categorize path");
 
-				if(path.size() == 0) path = "/";
+				if(path.size() == 0) path = "/";    /// \todo : use nana::filesystem_ext::def_rootstr?
 				_m_load_cat_path(path);
 			});
 
@@ -344,7 +347,7 @@ namespace nana
 			else
 				dir = saved_selected_path;
 
-			_m_load_cat_path(dir.size() ? dir : nana::experimental::filesystem::path_user().native());
+			_m_load_cat_path(dir.size() ? dir : fs_ext::path_user().native());
 
 			tb_file_.caption(file_with_path_removed);
 		}
@@ -427,10 +430,8 @@ namespace nana
 			nodes_.filesystem = tree_.insert("FS.ROOT", "Filesystem");
 			nodes_.filesystem.value(kind::filesystem);
 
-			namespace fs = ::nana::experimental::filesystem;
-
 			std::vector<std::string> paths;
-			paths.emplace_back(fs::path_user().native());
+			paths.emplace_back(fs_ext::path_user().native());
 			paths.emplace_back("/");
 
 			fs::directory_iterator end;
@@ -474,7 +475,7 @@ namespace nana
 			{
 				auto begstr = path.substr(0, pos);
 				if(begstr == "FS.HOME")
-					path.replace(0, 7, nana::experimental::filesystem::path_user().native());
+					path.replace(0, 7, fs_ext::path_user().native());
 				else
 					path.erase(0, pos);
 				return begstr;
@@ -490,8 +491,6 @@ namespace nana
 
 			file_container_.clear();
 
-			namespace fs = ::nana::experimental::filesystem;
-
 			fs::directory_iterator end;
 			for(fs::directory_iterator i(path); i != end; ++i)
 			{
@@ -508,13 +507,13 @@ namespace nana
 				{
 					m.bytes = fs::file_size(path + m.name);
 					m.directory = fs::is_directory(fattr);
-					::nana::experimental::filesystem::modified_file_time(path + m.name, m.modified_time);
+					fs_ext::modified_file_time(path + m.name, m.modified_time);
 				}
 				else
 				{
 					m.bytes = 0;
 					m.directory = fs::is_directory(*i);
-					::nana::experimental::filesystem::modified_file_time(path + i->path().filename().native(), m.modified_time);				
+					fs_ext::modified_file_time(path + i->path().filename().native(), m.modified_time);				
 				}
 
 				file_container_.push_back(m);
@@ -534,7 +533,7 @@ namespace nana
 			while(!beg_node.empty() && (beg_node != nodes_.home) && (beg_node != nodes_.filesystem))
 				beg_node = beg_node.owner();
 			
-			auto head = nana::experimental::filesystem::path_user().native();
+			auto head = fs_ext::path_user().native();
 			if(path.size() >= head.size() && (path.substr(0, head.size()) == head))
 			{//This is HOME
 				path_.caption("HOME");
@@ -552,7 +551,6 @@ namespace nana
 			if(head.size() == 0 || head[head.size() - 1] != '/')
 				head += '/';
 
-			namespace fs = ::nana::experimental::filesystem;
 
 			fs::directory_iterator end;
 			for(fs::directory_iterator i(head); i != end; ++i)
@@ -649,20 +647,20 @@ namespace nana
 					return;
 				}
 
-				using file_type = nana::experimental::filesystem::file_type;
+				using file_type = fs::file_type;
 
-				experimental::filesystem::path fspath(fb_.addr_.filesystem + path);
+				fs::path fspath(fb_.addr_.filesystem + path);
 
-				auto fs = experimental::filesystem::status(fspath);
+				auto fst = fs::status(fspath);
 
-				if(fs.type() != file_type::not_found && fs.type() != file_type::none)
+				if(fst.type() != file_type::not_found && fst.type() != file_type::none)
 				{
 					mb<<L"The folder is existing, please rename it.";
 					mb();
 					return;
 				}
 
-				if(false == experimental::filesystem::create_directory(fspath))
+				if(false == fs::create_directory(fspath))
 				{
 					mb<<L"Failed to create the folder, please rename it.";
 					mb();
@@ -756,7 +754,6 @@ namespace nana
 
 					bool good = true;
 
-					namespace fs = ::nana::experimental::filesystem;
 					auto fattr = fs::status(tar);
 					if(fattr.type() == fs::file_type::not_found)
 					{
@@ -809,8 +806,6 @@ namespace nana
 				auto path = tree_.make_key_path(node, "/") + "/";
 				_m_resolute_path(path);
 
-				namespace fs = ::nana::experimental::filesystem;
-
 				fs::directory_iterator end;
 				for (fs::directory_iterator i{path}; i != end; ++i)
 				{
@@ -952,7 +947,6 @@ namespace nana
 			}
 			else
 			{
-				namespace fs = ::nana::experimental::filesystem;
 				if (fs::is_directory(ipstr))
 					impl_->path = ipstr;
 			}
diff --git a/source/paint/detail/image_bmp.hpp b/source/paint/detail/image_bmp.hpp
index da86c0a3..23d7907e 100644
--- a/source/paint/detail/image_bmp.hpp
+++ b/source/paint/detail/image_bmp.hpp
@@ -13,8 +13,8 @@
 #ifndef NANA_PAINT_DETAIL_IMAGE_BMP_HPP
 #define NANA_PAINT_DETAIL_IMAGE_BMP_HPP
 
-#include "image_pixbuf.hpp"
 #include <memory>
+#include "image_pixbuf.hpp"
 
 namespace nana{	namespace paint
 {
@@ -309,7 +309,7 @@ namespace nana{	namespace paint
 				return true;
 			}
 
-			bool open(const nana::experimental::filesystem::path& filename) override
+			bool open(const std::experimental::filesystem::path& filename) override
 			{
 				std::ifstream ifs(filename.string(), std::ios::binary);
 				if(ifs)
diff --git a/source/paint/detail/image_ico.hpp b/source/paint/detail/image_ico.hpp
index debabac5..44b49191 100644
--- a/source/paint/detail/image_ico.hpp
+++ b/source/paint/detail/image_ico.hpp
@@ -1,8 +1,8 @@
 #ifndef NANA_PAINT_DETAIL_IMAGE_ICO_HPP
 #define NANA_PAINT_DETAIL_IMAGE_ICO_HPP
 
+#include <nana/filesystem/filesystem_ext.hpp>
 #include <nana/paint/detail/image_impl_interface.hpp>
-#include <nana/filesystem/filesystem.hpp>
 
 namespace nana{	namespace paint
 {
@@ -24,7 +24,7 @@ namespace nana{	namespace paint
 			image_ico(bool is_ico);
 
 
-			bool open(const ::nana::experimental::filesystem::path& filename) override;
+			bool open(const std::experimental::filesystem::path& filename) override;
 			bool open(const void* data, std::size_t bytes) override;
 			bool alpha_channel() const override;
 			bool empty() const override;
diff --git a/source/paint/detail/image_jpeg.hpp b/source/paint/detail/image_jpeg.hpp
index 2ae4b953..1f19373b 100644
--- a/source/paint/detail/image_jpeg.hpp
+++ b/source/paint/detail/image_jpeg.hpp
@@ -47,7 +47,7 @@ namespace nana
 				}
 			}
 		public:
-			bool open(const experimental::filesystem::path& jpeg_file) override
+			bool open(const std::experimental::filesystem::path& jpeg_file) override
 			{
 				auto fp = ::fopen(to_osmbstr(to_utf8(jpeg_file.native())).c_str(), "rb");
 				if(nullptr == fp) return false;
diff --git a/source/paint/image.cpp b/source/paint/image.cpp
index a1e2c889..b654ca6a 100644
--- a/source/paint/image.cpp
+++ b/source/paint/image.cpp
@@ -21,7 +21,7 @@
 
 #include <nana/paint/detail/image_impl_interface.hpp>
 #include <nana/paint/pixel_buffer.hpp>
-#include <nana/filesystem/filesystem.hpp>
+#include <nana/filesystem/filesystem_ext.hpp>
 
 #if defined(NANA_ENABLE_JPEG)
 #include "detail/image_jpeg.hpp"
@@ -36,6 +36,8 @@
 
 #include "image_accessor.hpp"
 
+namespace fs = std::experimental::filesystem;
+
 namespace nana
 {
 namespace paint
@@ -60,7 +62,7 @@ namespace paint
 		//class image_ico
 			image_ico::image_ico(bool is_ico): is_ico_(is_ico){}
 
-			bool image_ico::open(const nana::experimental::filesystem::path& file)
+			bool image_ico::open(const fs::path& file)
 			{
 				close();
 #if defined(NANA_WINDOWS)
@@ -231,7 +233,7 @@ namespace paint
 			return *this;
 		}
 
-		std::shared_ptr<image::image_impl_interface> create_image(const ::nana::experimental::filesystem::path & p)
+		std::shared_ptr<image::image_impl_interface> create_image(const fs::path & p)
 		{
 			std::shared_ptr<image::image_impl_interface> ptr;
 
@@ -314,14 +316,14 @@ namespace paint
 
 		bool image::open(const ::std::string& file)
 		{
-			::nana::experimental::filesystem::path path(file);
+			fs::path path(file);
 			image_ptr_ = create_image(path);
 			return (image_ptr_ ? image_ptr_->open(path) : false);
 		}
 
 		bool image::open(const std::wstring& file)
 		{
-			::nana::experimental::filesystem::path path(file);
+			fs::path path(file);
 			image_ptr_ = create_image(path);
 			return (image_ptr_ ? image_ptr_->open(path) : false);
 		}