grid deselection at header level doesnt work

Hi kowsalyavijayan ,

just try this logic

a!localVariables(
  local!items: {
    { item: "Item 1", qty: 1, unitPrice: 10 },
    { item: "Item 2", qty: 2, unitPrice: 20 }
  },
  local!selecteditems,
  a!gridLayout(
    label: "Products",
    instructions: "Selected: ",
    headerCells: {
      a!gridLayoutHeaderCell(label: "Item"),
      a!gridLayoutHeaderCell(label: "Qty"),
      a!gridLayoutHeaderCell(label: "Unit Price"),
      a!gridLayoutHeaderCell(label: "Total", align: "RIGHT")
    },
    rows: a!forEach(
      items: local!items,
      expression: a!gridRowLayout(
        id: fv!index,
        contents: {
          a!textField(
            value: fv!item.item,
            saveInto: fv!item.item
          ),
          a!integerField(value: fv!item.qty, saveInto: fv!item.qty),
          a!floatingPointField(
            value: fv!item.unitPrice,
            saveInto: fv!item.unitPrice
          ),
          a!textField(
            value: a!currency(
              isoCode: "USD",
              value: tointeger(fv!item.qty) * todecimal(fv!item.unitPrice)
            ),
            readOnly: true,
            align: "RIGHT"
          )
        }
      )
    ),
    selectable: true(),
    selectionValue: local!selecteditems,
    selectionSaveInto: a!save(
      local!selecteditems,
      a!flatten(save!value)
    ),
    rowHeader: 1
  )
)

You can try by replacing following code:

selectionSaveInto: {
      a!save(
        local!selectedIndex,
        a!flatten(save!value)
      ),
      a!save(
        local!selectedrows,
        if(
          a!isNullOrEmpty(local!selectedIndex),
          {},
          index(local!items, local!selectedIndex)
        )
      )
    }

Please go through below example by Appian 

https://docs.appian.com/suite/help/24.2/grid-with-selection-pattern.html

This works thank you