@Override
	public void stateChanged(ChangeEvent e) {
		Point viewPosition = viewport.getViewPosition();
		if (viewPosition.x != currentViewXpos) {
			currentViewXpos = viewPosition.x;
			notifyViewChanged();
		}
	}
Returns the last visible layout or null if there are no visible layouts

@return the last visible layout
Ghidra/Framework/Docking/src/main/java/docking/widgets/fieldpanel/FieldPanel.java