   yield return
 
 #-----------------------------------------------------------------------------------------------------------
-@_walk_opening_events = ( me ) ->
+@_walk_opening_events = ( me, layout_name_stack, field_selector_stack ) ->
   @_ensure_unitvector me
   layout_name       = me.name
   unitwidth_txt     = UNITS.as_text me.unitwidth

  me._tmp_is_outermost  = layout_name_stack.length < 2
  me._tmp_name          = layout_name_stack.join '/'
  ### Preparatory ###
  yield from @_walk_opening_events                      me
  yield from @_walk_style_events                        me ### TAINT should write to document preamble ###
  #.........................................................................................................
  ### Borders, content ###

  seen_fieldnrs           = new Set()
  selector                = @_resolve_aliases me, selector
  #.........................................................................................................
  ### TAINT must resolve aliases ###
  for term in selector
    if CND.isa_text term
      for cell from IG.GRID.walk_cells_from_selector me.grid, selector
