Go to Document Type->Add Property-> choose GridLayout as datatype->Configure gridLayout->Settings

adding following code

[
  {
    "label": "Class",
    "description": "Set a css class",
    "key": "class",
    "view": "radiobuttonlist",
    "prevalues": [
      "value_1",
      "value_2",
      "value_3"
    ]
  },
  {
    "label": "RowClass",
    "description": "Set a css class",
    "key": "class",
    "view": "radiobuttonlist",
    "prevalues": [
      "value_4",
      "value_5",
      "value_6"
    ],
    "applyTo": "row"
  }

]

Will This code work

what i want to do is let use select class property for sections as well as for row/cell

that is

on adding section has value 1-3 as class and row in section will have value4-6 as class, Cell Will have value 7-9 as class

is it possible Currently it is showing value 1-3 for editor,row,cell

Second Question: can we set default value as if client has generated a section and it has not any class than default class will come in place of empty div