# File lib/highline/system_extensions.rb, line 54
      def SetConsoleEcho( console_handle, on )
        mode = GetConsoleMode(console_handle)

        # toggle the console echo bit
        if on
          mode |=  ENABLE_ECHO_INPUT
        else
          mode &= ~ENABLE_ECHO_INPUT
        end

        ok = SetConsoleMode(console_handle, mode)    
      end