Question: How to obtain the coordinates from the map at the current mouse position?

src/eu/simstadt/regionchooser/RegionChooser.fxml

@@ -11,7 +11,7 @@
 
 <BorderPane fx:controller="eu.simstadt.regionchooser.RegionChooserController" maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefHeight="400.0" prefWidth="600.0" xmlns="http://javafx.com/javafx/8" xmlns:fx="http://javafx.com/fxml/1">
    <center>
-   <GoogleMapView fx:id="mapView" prefHeight="750.0" prefWidth="750.0" AnchorPane.bottomAnchor="0.0" AnchorPane.leftAnchor="0.0" AnchorPane.rightAnchor="0.0" AnchorPane.topAnchor="0.0"/>
+   <GoogleMapView onMouseClicked="#clicked" fx:id="mapView" prefHeight="750.0" prefWidth="750.0" AnchorPane.bottomAnchor="0.0" AnchorPane.leftAnchor="0.0" AnchorPane.rightAnchor="0.0" AnchorPane.topAnchor="0.0"/>
    </center>
    <bottom>
       <HBox BorderPane.alignment="CENTER">

src/eu/simstadt/regionchooser/RegionChooserController.java

 package eu.simstadt.regionchooser;
 
+import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
+
 import javafx.concurrent.Service;
 import javafx.concurrent.Task;
 import javafx.event.ActionEvent;
 import javafx.fxml.FXML;
 import javafx.scene.control.TextArea;
+
 import com.lynden.gmapsfx.GoogleMapView;
 import com.lynden.gmapsfx.MapComponentInitializedListener;
+import com.lynden.gmapsfx.javascript.JavascriptObject;
 import com.lynden.gmapsfx.javascript.object.GoogleMap;
 import com.lynden.gmapsfx.javascript.object.InfoWindow;
 import com.lynden.gmapsfx.javascript.object.InfoWindowOptions;
@@ -17,13 +21,14 @@
 import com.lynden.gmapsfx.javascript.object.MapTypeIdEnum;
 import com.lynden.gmapsfx.javascript.object.Marker;
 import com.lynden.gmapsfx.javascript.object.MarkerOptions;
+
 import eu.simstadt.nf.Coord;
 import eu.simstadt.nf.NFJobBuilder;
 
 
 public class RegionChooserController implements MapComponentInitializedListener
 {
-	List<Coord> regionPolygon;
+	ArrayList<Coord> regionPolygon = new ArrayList<>();
 
 	@FXML
 	private TextArea outputTA;
@@ -89,12 +94,10 @@ public void mapInitialized() {
 		InfoWindow bochumInfoWindow = new InfoWindow(infoWindowOptions);
 		bochumInfoWindow.open(map, bochumMarker);
 
-		regionPolygon = Arrays.asList(
-				new Coord(bochumLoc.getLatitude(), bochumLoc.getLongitude()),
-				new Coord(hamburgLoc.getLatitude(), bochumLoc.getLongitude()),
-				new Coord(stuttgartLoc.getLatitude(), bochumLoc.getLongitude()),
-				new Coord(dresdenLoc.getLatitude(), bochumLoc.getLongitude())
-				);
+		regionPolygon.add(new Coord(bochumLoc.getLatitude(), bochumLoc.getLongitude()));
+		regionPolygon.add(new Coord(hamburgLoc.getLatitude(), bochumLoc.getLongitude()));
+		regionPolygon.add(new Coord(stuttgartLoc.getLatitude(), bochumLoc.getLongitude()));
+		regionPolygon.add(new Coord(dresdenLoc.getLatitude(), bochumLoc.getLongitude()));
 	}
 
 	// Build the nF export job description from a region polygon
@@ -116,4 +119,23 @@ protected String call() throws Exception {
 		});
 		exportRunner.start();
 	}
+	
+	@FXML
+	void clicked() {
+		// Test, if this LatLong will be returned by getCenter(). Seams to work.
+		System.out.println("Center: " + map.getCenter());
+		
+		// Adding a fifth marker to the map seams to work without any problems.
+		LatLong loc = new LatLong(48.880003, 9.216849);
+		MarkerOptions markerOptions = new MarkerOptions();
+		markerOptions.position(loc);
+		Marker marker = new Marker(markerOptions);
+		map.addMarker(marker);
+		
+		// Now I want to obtain the current coordinates from the map at the mouse position in order 
+		// to instantiate and set a new marker.
+		//
+		// This statement fails. Why?
+		mapView.getMap().getLatLong();
+	}
 }
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