                  + " -- (#{right},#{bottom});", ]
     yield [ 'tex', "\n", ]
   #.........................................................................................................
+  yield [ 'tex', "\\end{scope}\n", ]
+  #.........................................................................................................
   yield return
 
 #-----------------------------------------------------------------------------------------------------------

  unless @_should_debug me
    yield return
  @_ensure_joint_coordinates  me
  #.........................................................................................................
  ### TAINT use fixed size like 1mm ###
  for [ col_letter, col_nr, ] from @_walk_column_letters_and_numbers me, 'short'

  unless @_should_debug me
    yield return
  #.........................................................................................................
  yield [ 'tex', "\\begin{scope}[on background layer]\n", ]
  #.........................................................................................................
  ### TAINT use fixed size like 1mm ###
  top       = ( @_top_from_row_nr     me, 1             ) - 3
  bottom    = ( @_bottom_from_row_nr  me, me.gridheight ) + 3
