@Override
	public Layout next() {
		Layout result = layoutModel.getLayout(index);
		lastIndex = index;
		index = layoutModel.getIndexAfter(index);
		return result;
	}
Returns the LayoutModel index of the previous item that was returned via {@link #next()}.

@return index of the previous Layout item returned, or null if this iterator hasn't been
used yet.
Ghidra/Framework/Docking/src/main/java/docking/widgets/fieldpanel/LayoutModelIterator.java