How is the border of the default dataview changed, or removed?

The default dataview seems to have light gray left and top border with a
darker gray right and bottom - even thought the borderstyle property is set
to Not set, the default setting?

It seems to be that if I set the borderstyle property none, then the right
and bottom borders disappear, but I am left with a grey left and top border.

What is going on, can anyone give me any explanation or references to help
me understand how the border of a dateview works.  What I reallz want is to
just have no border at all.