
procedure clear_pane(win, n, m, size)
   local x, y, width, height, save_fg

   width := n * size + 1
   height := m * size + 1

   save_fg := Fg(win)

   Fg(win, "black")

   every x := 0 to width by size do
      DrawLine(win, x, 0, x, height)

   every y := 0 to height by size do
      DrawLine(win, 0, y, width, y)

   Fg(win, save_fg)

   return

end
