property ImportPreferences;
Bit-set controlling how ImportPages copies content (resources, named destinations, comments, etc.).
Set before calling ImportPages.
Wraps the corresponding PDFium API and exposes it as a TPdf instance member so consumers do not have to manage FPDF_DOCUMENT handles directly.
Pdf1.Active before calling page-scoped operations; methods that require an open document raise EPdfError otherwise.SaveToFile to persist.
if Pdf1.Active then
Pdf1.ImportPreferences;