added a sample nested controller

src/main/java/kellerkinder/HomeFlix/application/FilmDetailView.java

@@ -0,0 +1,18 @@
+package kellerkinder.HomeFlix.application;
+
+import javafx.fxml.FXML;
+import javafx.scene.control.Label;
+
+public class FilmDetailView {
+	
+	@FXML private Label lblFilm;
+	
+	public void initialize() {
+		System.out.println("init nested controller");
+	}
+	
+	public void foo() {
+		System.out.println("test");
+	}
+
+}

src/main/java/kellerkinder/HomeFlix/application/Main.java

@@ -34,6 +34,7 @@ import javafx.application.Application;
 import javafx.event.ActionEvent;
 import javafx.event.EventHandler;
 import javafx.fxml.FXMLLoader;
+import javafx.scene.Parent;
 import javafx.scene.Scene;
 import javafx.scene.image.Image;
 import javafx.scene.layout.AnchorPane;

src/main/java/kellerkinder/HomeFlix/application/MainWindowController.java

@@ -163,6 +163,9 @@ public class MainWindowController {
 	// poster-mode
 	@FXML private ScrollPane posterModeScrollPane;
 	@FXML private FlowPane posterModeFlowPane;
+
+	// FilmDetailView
+	@FXML private FilmDetailView filmDetailViewController;
 	
 	private DBController dbController;
 	private UpdateController updateController;
@@ -498,6 +501,7 @@ public class MainWindowController {
 	@FXML
 	private void returnBtnclicked() {
 		filmsTreeTable.getSelectionModel().select(last);
+		filmDetailViewController.foo();
 	}
 
 	@FXML

src/main/resources/fxml/FilmDetailView.fxml

@@ -0,0 +1,10 @@
+<?xml version="1.0" encoding="UTF-8"?>
+
+<?import javafx.scene.control.Label?>
+<?import javafx.scene.layout.AnchorPane?>
+
+<AnchorPane prefHeight="568.0" prefWidth="980.0" xmlns="http://javafx.com/javafx/11.0.1" xmlns:fx="http://javafx.com/fxml/1" fx:controller="kellerkinder.HomeFlix.application.FilmDetailView">
+   <children>
+      <Label fx:id="lblFilm" layoutX="461.0" layoutY="277.0" text="Test Pane" />
+   </children>
+</AnchorPane>

src/main/resources/fxml/MainWindow.fxml

@@ -74,6 +74,9 @@
             </FlowPane>
          </content>
       </ScrollPane>
+	  <AnchorPane>
+		 <fx:include source="/fxml/FilmDetailView.fxml" fx:id="filmDetailView" />
+	  </AnchorPane>
       <ScrollPane fx:id="settingsScrollPane" fitToHeight="true" fitToWidth="true" prefHeight="568.0" prefWidth="800.0" style="-fx-background: white;" visible="false" AnchorPane.bottomAnchor="0.0" AnchorPane.leftAnchor="150.0" AnchorPane.rightAnchor="0.0" AnchorPane.topAnchor="32.0">
         <content>
           <AnchorPane fx:id="settingsAnchorPane" style="-fx-background-color: white;">