def print_center(htext, r = 0, c = 0)
      win = @window
      len = win.getmaxx
      len = Ncurses.COLS-0 if len == 0 || len > Ncurses.COLS
      #
      win.printstring r, ((len-htext.length)/2).floor, htext, @color_pair, @attr
    end
def print_center(htext, r = 0, c = 0)
      win = @window
      len = win.getmaxx
      len = Ncurses.COLS-0 if len == 0 || len > Ncurses.COLS
      #
      win.printstring r, ((len-htext.length)/2).floor, htext, @color_pair, @attr
    end
internal method, called by repaint to print text_center in the center