SetCanvasGeometry
oldOffset = mask->SetCanvasGeometry(IntPoint(0, 0), boundingBox);
mask->SetCanvasGeometry(oldOffset, boundingBox);
fCanvas->CurrentState()->GetAlphaMask()->SetCanvasGeometry(BPoint(0, 0),
fCanvas->CurrentState()->GetAlphaMask()->SetCanvasGeometry(BPoint(0, 0),
fCanvas->CurrentState()->GetAlphaMask()->SetCanvasGeometry(BPoint(0, 0),
view->GetAlphaMask()->SetCanvasGeometry(leftTop, view->Bounds());
fPreviousMask->SetCanvasGeometry(origin, bounds);
IntPoint SetCanvasGeometry(IntPoint origin,