Convert characters from the locale's encoding on output.

Reject characters outside the locale's encoding on input.

Tools/idle/PyShell.py

@@ -191,7 +191,12 @@ def runsource(self, source):
         warnings.filterwarnings(action="error", category=SyntaxWarning)
         if isinstance(source, types.UnicodeType):
             import IOBinding
-            source = source.encode(IOBinding.encoding)
+            try:
+                source = source.encode(IOBinding.encoding)
+            except UnicodeError:
+                self.tkconsole.resetoutput()
+                self.write("Unsupported characters in input")
+                return
         try:
             return InteractiveInterpreter.runsource(self, source, filename)
         finally: