LayoutArea
BRect LayoutArea();
BRect layoutArea = GroupLayout()->LayoutArea();
BSize size(LayoutArea().Size());
fVisibleItem->AlignInFrame(BRect(LayoutArea().LeftTop(), size));
BSize size = _SubtractInsets(LayoutArea().Size());
BSize size = _SubtractInsets(LayoutArea().Size());
BSize size = _SubtractInsets(LayoutArea().Size());
BSize size(SubtractInsets(LayoutArea().Size()));
BPoint itemOffset(LayoutArea().LeftTop());
BSize viewSize = LayoutArea().Size();
AreaFor(ItemAt(i))->_DoLayout(LayoutArea().LeftTop());
BSize size(layout->LayoutArea().Size());