fix syntax error and add workarounds for libstdc++

source/system/dataexch.cpp

@@ -1,6 +1,6 @@
 /*
  *	Data Exchanger Implementation
- *	Copyright(C) 2003-2015 Jinhao(cnjinhao@hotmail.com)
+ *	Copyright(C) 2003-2017 Jinhao(cnjinhao@hotmail.com)
  *
  *	Distributed under the Boost Software License, Version 1.0.
  *	(See accompanying file LICENSE_1_0.txt or copy at
@@ -116,7 +116,8 @@ namespace nana{ namespace system{
 //#elif defined(NANA_X11)
 #else
 			static_cast<void>(g); //eliminate unused parameter compiler warning.
-			throw "not implemented yet.";
+			static_cast<void>(owner);
+			throw std::logic_error("dataexch::set(const paint::graphics&, native_window_type owner) not implemented yet.");
 			return false;
 #endif
 		}