def remove_last_word lineno
      @list[lineno].chomp!
      line=@list[lineno]
      lastspace = line.rindex(" ")
      if !lastspace.nil?
        lastchars = line[lastspace+1..-1]
        @list[lineno].slice!(lastspace..-1)
        $log.debug " remove_last: lastspace #{lastspace},#{lastchars},#{@list[lineno]}"
        fire_handler :CHANGE, InputDataEvent.new(lastspace,lastchars.length, self, :DELETE, lineno, lastchars)     #  2008-12-26 23:06 
        return lastchars
      end
      return nil
    end
def remove_last_word lineno
      @list[lineno].chomp!
      line=@list[lineno]
      lastspace = line.rindex(" ")
      if !lastspace.nil?
        lastchars = line[lastspace+1..-1]
        @list[lineno].slice!(lastspace..-1)
        $log.debug " remove_last: lastspace #{lastspace},#{lastchars},#{@list[lineno]}"
        fire_handler :CHANGE, InputDataEvent.new(lastspace,lastchars.length, self, :DELETE, lineno, lastchars)     #  2008-12-26 23:06 
        return lastchars
      end
      return nil
    end
removes and returns last word in given line number, or nil if no whitespace