Polyline inside and tangent to polyline

Hi all,
I need to be able to understand if a poly is contained inside another
poly. I'm using SelectByPolygon with acSelectionSetCrossingPolygon
option. The problem is that in this way an external poly tangent to
another one is considered inside.
I try to explain the problem better.
Let's say you have poly A, which contains and share a side with poly B.
Poly A is also tangent to an external poly C. Well, the selection
acSelectionSetCrossingPolygon poly A will contain poly B and C and not
only B. How can I understand if a poly is really contained and not only
tanget to another one?
Thanks.

-----------
|A |------ PS: Sorry for the poor ascii art!
| ---| C|
| |B | |
| ---| |
| | |
| |------
-----------

 

Use acSelectionSetWindowPolygon

 

Thanks for the answer but using acSelectionSetWindowPolygon will not
select an internal poly which is tangent to the container poly.
Referring to my previous example, B would not be present in the
selection.