Are you stalking me? ;o)
Sorry I have to disagree with you - windows and doors don't solely follow the cut plane of the view - it is a combination of both the view range in the project and the view range in the family. . This is nothing to do with masking regions or symbolic lines.
See image below for an example of the issue - first 2 families are windows with different cut planes set in the family itself, the 3rd window is the same family but changed to the generic model category - this is the only one that correctly shows the window as it should be cut by the view range in the project.
When you start getting into nested families it gets even more complicated. Honestly the fact the that view range / cut plane in the the family has any bearing on how the element shows in the project is frankly just confusing.
One of my main reasons for looking for this is to try and deal with the issues of windows that span over more than one floor.