diff --git a/include/nana/gui/widgets/checkbox.hpp b/include/nana/gui/widgets/checkbox.hpp
index 8d06b590..e3b31d69 100644
--- a/include/nana/gui/widgets/checkbox.hpp
+++ b/include/nana/gui/widgets/checkbox.hpp
@@ -1,7 +1,7 @@
 /**
  *	A CheckBox Implementation
  *	Nana C++ Library(http://www.nanapro.org)
- *	Copyright(C) 2003-2016 Jinhao(cnjinhao@hotmail.com)
+ *	Copyright(C) 2003-2018 Jinhao(cnjinhao@hotmail.com)
  *
  *	Distributed under the Boost Software License, Version 1.0. 
  *	(See accompanying file LICENSE_1_0.txt or copy at 
@@ -100,6 +100,7 @@ namespace drawerbase
 			event_handle eh_keyboard;
 		};
 	public:
+		constexpr static const std::size_t npos = static_cast<std::size_t>(-1);
 		~radio_group();
 		void add(checkbox&);
 		std::size_t checked() const;       ///< Retrieves the index of the checkbox which is checked.
diff --git a/include/nana/gui/widgets/group.hpp b/include/nana/gui/widgets/group.hpp
index 2e264289..1985c961 100644
--- a/include/nana/gui/widgets/group.hpp
+++ b/include/nana/gui/widgets/group.hpp
@@ -1,7 +1,7 @@
 /**
  *	A group widget implementation
  *	Nana C++ Library(http://www.nanaro.org)
- *	Copyright(C) 2015 Jinhao(cnjinhao@hotmail.com)
+ *	Copyright(C) 2015-2018 Jinhao(cnjinhao@hotmail.com)
  *
  *	Distributed under the Boost Software License, Version 1.0. 
  *	(See accompanying file LICENSE_1_0.txt or copy at 
@@ -28,6 +28,7 @@ namespace nana{
 		struct implement;
 	public:
 		using field_reference = place::field_reference;
+		constexpr static const std::size_t npos = static_cast<std::size_t>(-1);
 
 		/// The default construction
 		group();
@@ -63,8 +64,8 @@ namespace nana{
 
 		group& enable_format_caption(bool format);
 
-		group& collocate() throw();
-		group& div(const char* div_str) throw();
+		group& collocate() noexcept;
+		group& div(const char* div_str) noexcept;
 		field_reference operator[](const char* field);
 		
 		template<typename Widget, typename ...Args>
diff --git a/source/gui/widgets/checkbox.cpp b/source/gui/widgets/checkbox.cpp
index a1b2fe5c..7fc20469 100644
--- a/source/gui/widgets/checkbox.cpp
+++ b/source/gui/widgets/checkbox.cpp
@@ -1,7 +1,7 @@
 /*
  *	A CheckBox Implementation
  *	Nana C++ Library(http://www.nanapro.org)
- *	Copyright(C) 2003-2017 Jinhao(cnjinhao@hotmail.com)
+ *	Copyright(C) 2003-2018 Jinhao(cnjinhao@hotmail.com)
  *
  *	Distributed under the Boost Software License, Version 1.0.
  *	(See accompanying file LICENSE_1_0.txt or copy at
@@ -296,7 +296,7 @@ namespace nana{ namespace drawerbase
 					return static_cast<std::size_t>(i - ui_container_.cbegin());
 			}
 
-			return ui_container_.size();
+			return npos;
 		}
 
 		std::size_t radio_group::size() const
diff --git a/source/gui/widgets/group.cpp b/source/gui/widgets/group.cpp
index 87d2ebc6..f84058ea 100644
--- a/source/gui/widgets/group.cpp
+++ b/source/gui/widgets/group.cpp
@@ -1,7 +1,7 @@
 /**
  *	A group widget implementation
  *	Nana C++ Library(http://www.nanaro.org)
- *	Copyright(C) 2015-2017 Jinhao(cnjinhao@hotmail.com)
+ *	Copyright(C) 2015-2018 Jinhao(cnjinhao@hotmail.com)
  *
  *	Distributed under the Boost Software License, Version 1.0. 
  *	(See accompanying file LICENSE_1_0.txt or copy at 
@@ -172,13 +172,13 @@ namespace nana{
 		return *this;
 	}
 
-	group& group::collocate() throw ()
+	group& group::collocate() noexcept
 	{
 		impl_->place_content.collocate();
 		return *this;
 	}
 
-	group& group::div(const char* div_str) throw ()
+	group& group::div(const char* div_str) noexcept
 	{
 		if (div_str)
 			impl_->usr_div_str = div_str;