Flattens the transparent objects on pages in
When transparent objects overlap other
objects, all or a portion of the overlapped object shows through.
FlattenTransparency will create new objects that represent the
portion of the two objects that overlap. Portions of transparent
objects that don't overlap other objects are composited with the
backdrop color (white) to create a fully opaque object that appears
Note that this feature is only available under the ABCpdf