Ok, with a little help from a friend, I did some testing. This is what I
came up with.
I tested by changing the background color of the form. In Tabs or Buttons
style, the body of the tab control is transparent, the tab/button bar isn't.
Since the None style removes this, that makes the whole thing transparent.
In None style, it is still possible to change pages using code.
Example:
Me.TabCtl0.Pages("Page2").SetFocus
So, you could create your own buttons to change the pages, giving you a
transparent look for the tab control.
This was done in Access 2003.