Well, it's a bit complicated and the second property (IsUnmodifiedTemplateAddRow) has a somewhat misleading name.

Basically, as soon as you click onto a TemplateAddRow, it ceases to be a TemplateAddRow. It becomes an AddRow and it exists in the DataSource. So at that point, IsTemplateAddRow returns false, even if you have not made any changes to the row.

However, even though it's an AddRow and exists in the data source, the grid still treats it differently than a normal AddRow. If you click away from the row without modifying it, for example, the grid cancels the add row. It would not normally do this, it only does it for an AddRow that is not modified and used to be a TemplateAddRow. So IsUnmodifiedTemplateAddRow really indicates that the row is an unmodified AddRow that will be canceled if there are no changes, because it's being treated as a TemplateAddRow, even though it's technically not a TemplateAddRow any more. \

But IsUnmodifiedAddRowThatIsBeingTreatedAsATemplateAddRowBecauseItUsedToBeOne was a bit unwieldy as a property name. So we had to abbreviate it a little at the cost of some potential confusion. :)