def render_all pad, arr
      pre_render
      @content_cols = @source.pad_cols
      @clearstring = " " * @content_cols
      @list = arr

      att = @attr || NORMAL
      FFI::NCurses.wattron(pad, @cp | att)

      arr.each_with_index { |line, ix|
        render pad, ix, line
      }
      FFI::NCurses.wattroff(pad, @cp | att)
    end
def render_all pad, arr
      pre_render
      @content_cols = @source.pad_cols
      @clearstring = " " * @content_cols
      @list = arr

      att = @attr || NORMAL
      FFI::NCurses.wattron(pad, @cp | att)

      arr.each_with_index { |line, ix|
        render pad, ix, line
      }
      FFI::NCurses.wattroff(pad, @cp | att)
    end
derived classes may choose to override this.
 However, they should set size and color and attrib at the start since these
 can change after the object has been created depending on the application.