add OFN_NOCHANGEDIR flag to OPENFILENAME::Flags in nana::filebox::show

http://blogs.msdn.com/b/oldnewthing/archive/2010/11/12/10089878.aspx
	setting OFN_NOCHANGEDIR flag to OPENFILENAME::Flags is effective for GetOpenFileName API on Windows7.
add const qualifier to nana::paint::graphics::save_as_file
add support for small icon on Windows.
	The system displays the large icon in the ALT+TAB dialog box, and the small icon in the window caption.
	https://msdn.microsoft.com/en-us/library/windows/desktop/ms632643%28v=vs.85%29.aspx

include/nana/gui/detail/native_window_interface.hpp

@@ -45,6 +45,8 @@ namespace detail
 		static void enable_dropfiles(native_window_type, bool);
 		static void enable_window(native_window_type, bool);
 		static bool window_icon(native_window_type, const paint::image&);
+		// (On Windows) The system displays the large icon in the ALT+TAB dialog box, and the small icon in the window caption.
+		static bool window_icon(native_window_type, const paint::image& big_icon, const paint::image& small_icon);
 		static void activate_owner(native_window_type);
 		static void activate_window(native_window_type);
 		static void close_window(native_window_type);

include/nana/gui/detail/window_manager.hpp

@@ -112,7 +112,6 @@ namespace detail
 		void signal_fire_caption(core_window_t*, const nana::char_t*);
 		nana::string signal_fire_caption(core_window_t*);
 		void event_filter(core_window_t*, bool is_make, event_code);
-		void default_icon(const nana::paint::image&);
 
 		bool available(core_window_t*);
 		bool available(core_window_t *, core_window_t*);
@@ -133,7 +132,10 @@ namespace detail
 		//@brief:	Delete window handle, the handle type must be a root and a frame.
 		void destroy_handle(core_window_t*);
 
+		void default_icon(const paint::image&);
+		void default_icon(const paint::image& big_icon, const paint::image& small_icon);
 		void icon(core_window_t*, const paint::image&);
+		void icon(core_window_t*, const paint::image& big_icon, const paint::image& small_icon);
 
 		//show
 		//@brief: show or hide a window

include/nana/gui/programming_interface.hpp

@@ -120,7 +120,10 @@ namespace API
 	}
 
 	void window_icon_default(const paint::image&);
+	void window_icon_default(const paint::image& big_icon, const paint::image& small_icon);
 	void window_icon(window, const paint::image&);
+	void window_icon(window, const paint::image& big_icon, const paint::image& small_icon);
+	
 	bool empty_window(window);		///< Determines whether a window is existing.
 	bool is_window(window);			///< Determines whether a window is existing, equal to !empty_window.
 	void enable_dropfiles(window, bool);

include/nana/paint/detail/image_bmp.hpp

@@ -75,6 +75,12 @@ namespace nana{	namespace paint
 				this->close();
 			}
 
+			bool open(void* buff, size_t sz)
+			{
+				// TODO: read a BMP file from memory
+				return false;
+			}
+
 			bool open(const nana::char_t* filename)
 			{
 				if(nullptr == filename) return false;

include/nana/paint/detail/image_ico.hpp

@@ -23,6 +23,7 @@ namespace nana{	namespace paint
 			image_ico(bool is_ico);
 
 			bool open(const nana::char_t* filename);
+			bool open(void* buff, size_t sz);
 			bool alpha_channel() const;
 			bool empty() const;
 			void close();

include/nana/paint/detail/image_impl_interface.hpp

@@ -16,6 +16,7 @@ namespace nana{	namespace paint{
 		typedef nana::paint::graphics& graph_reference;
 		virtual ~image_impl_interface() = 0;	//The destructor is defined in ../image.cpp
 		virtual bool open(const nana::char_t* filename) = 0;
+		virtual bool open(void* buff, size_t sz) = 0; // reads image from memory
 		virtual bool alpha_channel() const = 0;
 		virtual bool empty() const = 0;
 		virtual void close() = 0;

include/nana/paint/graphics.hpp

@@ -130,7 +130,7 @@ namespace nana
 			void setsta();      ///<  	Clears the status if the graphics object had been changed
 			void set_changed();
 			void release();
-			void save_as_file(const char*);
+			void save_as_file(const char*) const;	// saves image as a bitmap file
 
 			void set_color(const ::nana::color&);
 			void set_text_color(const ::nana::color&);

include/nana/paint/image.hpp

@@ -37,6 +37,7 @@ namespace paint
 		image& operator=(const image& rhs);
 		image& operator=(image&&);
 		bool open(const nana::string& filename);
+		bool open_icon(void* buff, size_t sz);	// opens a icon from memory
 		bool empty() const;
 		operator unspecified_bool_t() const;
 		void close();

source/gui/detail/native_window_interface.cpp

@@ -537,6 +537,30 @@ namespace nana{
 			return false;
 		}
 
+		bool native_interface::window_icon(native_window_type wd, const paint::image& big_icon, const paint::image& small_icon)
+		{
+#if defined(NANA_WINDOWS)
+			HICON h_big_icon = paint::image_accessor::icon(big_icon);
+			HICON h_small_icon = paint::image_accessor::icon(small_icon);
+			if (h_big_icon || h_small_icon)
+			{
+				nana::detail::platform_spec::instance().keep_window_icon(wd, (!big_icon.empty() ? big_icon : small_icon));
+				if (h_big_icon) {
+					::SendMessage(reinterpret_cast<HWND>(wd), WM_SETICON, ICON_BIG, reinterpret_cast<LPARAM>(h_big_icon));
+				}
+				if (h_small_icon) {
+					::SendMessage(reinterpret_cast<HWND>(wd), WM_SETICON, ICON_SMALL, reinterpret_cast<WPARAM>(h_small_icon));
+				}
+				return true;
+			}
+#elif defined(NANA_X11)
+			return window_icon(wd, big_icon);
+#endif
+			return false;
+		}
+
+
+
 		void native_interface::activate_owner(native_window_type wd)
 		{
 #if defined(NANA_WINDOWS)

source/gui/detail/window_manager.cpp

@@ -43,7 +43,8 @@ namespace detail
 				root_register	misc_register;
 				handle_manager<core_window_t*, window_manager, window_handle_deleter>	wd_register;
 				signal_manager	signal;
-				paint::image default_icon;
+				paint::image default_icon_big;
+				paint::image default_icon_small;
 			};
 		//end struct wdm_private_impl
 
@@ -199,11 +200,6 @@ namespace detail
 			}
 		}
 
-		void window_manager::default_icon(const paint::image& img)
-		{
-			impl_->default_icon = img;
-		}
-
 		bool window_manager::available(core_window_t* wd)
 		{
 			return impl_->wd_register.available(wd);
@@ -264,7 +260,7 @@ namespace detail
 					insert_frame(owner, wd);
 
 				bedrock::inc_window(wd->thread_id);
-				this->icon(wd, impl_->default_icon);
+				this->icon(wd, impl_->default_icon_big, impl_->default_icon_small);
 				return wd;
 			}
 			return nullptr;
@@ -404,6 +400,18 @@ namespace detail
 			}
 		}
 
+		void window_manager::default_icon(const paint::image& img)
+		{
+			impl_->default_icon_big = img;
+			impl_->default_icon_small = img;
+		}
+
+		void window_manager::default_icon(const nana::paint::image& big, const nana::paint::image& small)
+		{
+			impl_->default_icon_big = big;
+			impl_->default_icon_small = small;
+		}
+
 		void window_manager::icon(core_window_t* wd, const paint::image& img)
 		{
 			if(false == img.empty())
@@ -417,6 +425,19 @@ namespace detail
 			}
 		}
 
+		void window_manager::icon(core_window_t* wd, const paint::image& big_icon, const paint::image& small_icon)
+		{
+			if(!big_icon.empty() || !small_icon.empty())
+			{
+				std::lock_guard<decltype(mutex_)> lock(mutex_);
+				if (impl_->wd_register.available(wd))
+				{
+					if(wd->other.category == category::root_tag::value)
+						native_interface::window_icon(wd->root, big_icon, small_icon);
+				}
+			}
+		}
+
 		//show
 		//@brief: show or hide a window
 		bool window_manager::show(core_window_t* wd, bool visible)

source/gui/filebox.cpp

@@ -1021,6 +1021,7 @@ namespace nana
 			
 			if (!impl_->open_or_save)
 				ofn.Flags = OFN_OVERWRITEPROMPT;	//Overwrite prompt if it is save mode
+			ofn.Flags |= OFN_NOCHANGEDIR;
 			
 			if(FALSE == (impl_->open_or_save ? ::GetOpenFileName(&ofn) : ::GetSaveFileName(&ofn)))
 				return false;

source/gui/programming_interface.cpp

@@ -359,11 +359,21 @@ namespace API
 		restrict::window_manager.default_icon(img);
 	}
 
+	void window_icon_default(const paint::image& big_icon, const paint::image& small_icon)
+	{
+		restrict::window_manager.default_icon(big_icon, small_icon);
+	}
+
 	void window_icon(window wd, const paint::image& img)
 	{
 		restrict::window_manager.icon(reinterpret_cast<restrict::core_window_t*>(wd), img);
 	}
 
+	void window_icon(window wd, const paint::image& big_icon, const paint::image& small_icon)
+	{
+		restrict::window_manager.icon(reinterpret_cast<restrict::core_window_t*>(wd), big_icon, small_icon);
+	}
+
 	bool empty_window(window wd)
 	{
 		return (restrict::window_manager.available(reinterpret_cast<restrict::core_window_t*>(wd)) == false);

source/paint/graphics.cpp

@@ -812,7 +812,7 @@ namespace paint
 			size_.width = size_.height = 0;
 		}
 
-		void graphics::save_as_file(const char* file)
+		void graphics::save_as_file(const char* file) const
 		{
 			if(handle_)
 			{

source/paint/image.cpp

@@ -69,6 +69,31 @@ namespace paint
 				return false;
 			}
 
+			bool image_ico::open(void* buff, size_t sz)
+			{
+				close();
+#if defined(NANA_WINDOWS)
+				HICON handle = CreateIconFromResource((PBYTE)buff, sz, TRUE, 0x00030000);
+				if(handle)
+				{
+					ICONINFO info;
+					if (::GetIconInfo(handle, &info) != 0)
+					{
+						HICON * p = new HICON(handle);
+						ptr_ = std::shared_ptr<HICON>(p, handle_deleter());
+						size_.width = (info.xHotspot << 1);
+						size_.height = (info.yHotspot << 1);
+						::DeleteObject(info.hbmColor);
+						::DeleteObject(info.hbmMask);
+						return true;
+					}
+				}
+#else
+				if(is_ico_){}	//kill the unused compiler warning in Linux.
+#endif
+				return false;
+			}
+
 			bool image_ico::alpha_channel() const
 			{
 				return false;
@@ -235,6 +260,13 @@ namespace paint
 			return false;
 		}
 
+		bool image::open_icon(void* buff, size_t sz)
+		{
+			image::image_impl_interface * helper = new detail::image_ico(true);
+			image_ptr_ = std::shared_ptr<image_impl_interface>(helper);
+			return helper->open(buff, sz);
+		}
+
 		bool image::empty() const
 		{
 			return ((nullptr == image_ptr_) || image_ptr_->empty());