code: private void updateMaxExtent() {
  		if (targetMap.getMapModel().isInitialized() && getGraphics().isReady()) {
  			// map view size may not have been set yet !
  			getMapModel().getMapView().setSize(getWidth(), getHeight());
  			Bbox targetMaxBounds = getOverviewMaxBounds();
  
  			MapView mapView = getMapModel().getMapView();
  
  			// Set the maxBounds on this map as well:
  			mapView.setMaxBounds(targetMaxBounds.buffer(targetMaxBounds.getWidth()));
  
  			// apply buffer
  			if (maxExtentIncreasePercentage > 0) {
  				targetMaxBounds = targetMaxBounds
  						.buffer(targetMaxBounds.getWidth() * maxExtentIncreasePercentage / 100);
  			}
  
  			// Then apply the map extent:
  			mapView.applyBounds(targetMaxBounds, MapView.ZoomOption.LEVEL_FIT);
  
  			// Immediately draw or remove the max extent rectangle:
  			setDrawTargetMaxExtent(drawTargetMaxExtent);
  		}
  	}
docs: Apply a maximum extent. This will extend the map extend to be used by the percentage to increase.