def _clear_row pad, lineno
      raise "unused"
      @color_pair ||= get_color($datacolor, @source.color, @source.bgcolor)
      cp = @color_pair
      att = NORMAL
      @_clearstring ||= " " * (@source.width - @left_margin - @int_w)
      # with int_w = 3 we get that one space in popuplist
      # added attr on 2014-05-02 - 00:16 otherwise a list inside a white bg messagebox shows
      # empty rows in black bg.
      FFI::NCurses.wattron(pad,FFI::NCurses.COLOR_PAIR(cp) | att)
      FFI::NCurses.mvwaddstr(pad,lineno, @left_margin, @_clearstring) 
      FFI::NCurses.wattroff(pad,FFI::NCurses.COLOR_PAIR(cp) | att)
    end
def _clear_row pad, lineno
      raise "unused"
      @color_pair ||= get_color($datacolor, @source.color, @source.bgcolor)
      cp = @color_pair
      att = NORMAL
      @_clearstring ||= " " * (@source.width - @left_margin - @int_w)
      # with int_w = 3 we get that one space in popuplist
      # added attr on 2014-05-02 - 00:16 otherwise a list inside a white bg messagebox shows
      # empty rows in black bg.
      FFI::NCurses.wattron(pad,FFI::NCurses.COLOR_PAIR(cp) | att)
      FFI::NCurses.mvwaddstr(pad,lineno, @left_margin, @_clearstring) 
      FFI::NCurses.wattroff(pad,FFI::NCurses.COLOR_PAIR(cp) | att)
    end
clear row before writing so previous contents are erased and don't show through
 I could do this everytime i write but trying to make it faster
 and only call this if +fire_row_changed+ is called.
 NOTE: in clear_row one is supposed to clear to the width of the pad, not window
   otherwise on scrolling you might get black bg if you have some other color bg.
   This is mostly important if you have a bgcolor that is different from the terminal
   bgcolor.
 @param - pad
 @param - line number (index of row to clear)