Selection.Intersect Method (Visio)
Creates one closed shape from the area in which selected shapes overlap or intersect.
Calling the Intersect method is equivalent to clicking Intersect in the Microsoft Visio user interface (click Operations in the Shape Design group on the Developer tab). The produced shape will be the topmost shape in its containing shape and will inherit the text and formatting of the first selected shape.
The original shapes are deleted and no shapes are selected when the operation is complete.