property ChangePageOnMouseScrolling: Boolean;
SinglePage mode では、page edge での mouse-wheel scrolling で次の page に進むかどうかを制御します
Has no effect in continuous DisplayMode values.
All TPdfView display properties trigger a repaint when assigned; you can change several in sequence without flicker because the redraw is coalesced into a single invalidation.
Active := True.PdfView1.Pdf at runtime, re-apply any view-only settings — the new TPdf has its own state.
begin
PdfView1.ChangePageOnMouseScrolling := {value};
PdfView1.Active := True;
end;