To Enable/disable Editing on new/existing row in datawindow

 //In your datawindow write this code in your column property, in ->General->protect

if (isRowNew(), 0, 1)

//this will enable editing on newrow and disable editing on existing row

//write code in each column to enable/disable editing for a row...

//you can put other conditions like calculation such as

if (columnname = 'Admin', 0, 1)