This class has a method used for retrieving other shapes in the
current editing context. This class provides a way for the
BezierShape::PerformTrimOrExtend
method to access the shapes being trimmed.
This method will be called with a
ModContext pointer; the function should return the shape for
that context. This is only used in modifier applications, where
more than one shape object is being modified. See
/MAXSDK/SAMPLES/MODIFIERS/EDITSPL.CPP for an example of its
use.