How to make checkbox Editable without making the all cells editable.

Hi!

Let me describe my problem.

I have such an itab

data: begin of itab occurs 0,

chk(1) Type C,

matnr like mara matnr ,

maktx like makt-maktx,

end of itab.

I have made the field catalog of check box field appropriately.

wa_fieldcat-checkbox = 'X'.

wa_fieldcat-edit = 'X'.

but without making the layout-edit = 'X' THE CHECKBOXS are UNEDITABLE.

I can not click and change the state of the checkboxes.It only display the checkboxes but no click is available.

When the layout-edit = 'X' is given all the column is the grid are editable. and this is certainly is not what I want.

How can I remedy this problem ?

Kind Regards.