title: JavaFX Issue with always-visible-datepicker
body: <p>Iam trying to create a datepicker which is always open(popup).So i got a working code from githhub link <a href="https://gist.github.com/flasheater/ba58d5adffa1324e727e" rel="nofollow noreferrer">https://gist.github.com/flasheater/ba58d5adffa1324e727e</a>.
  But my problem is when i implemented this code on my controller class it showing error.So i would like to post my complete code below.</p>
  
  <p>FXMLDocumentController.java</p>
  
  <pre><code>  public class FXMLDocumentController implements Initializable {
    @FXML
    private AnchorPane bp;
    @Override
    public void initialize(URL url, ResourceBundle rb) {
      final DatePicker date_picker = new DatePicker();
      StackPane root=new StackPane(date_picker);
      date_picker.setVisible( false );
      date_picker.setManaged( false );
  
     final com.sun.javafx.scene.control.skin.DatePickerSkin skin = (com.sun.javafx.scene.control.skin.DatePickerSkin) date_picker.getSkin();
     root.getChildren().add(skin.getPopupContent()); 
     //added to stackpane.I think above line is having problem
     bp.getChildren().add(root); //added to anchorpane which already designed via scenebuilder
  }
  }
  </code></pre>
  
  <p>FXMLDocument.fxml(designed via scenebuilder2.0)</p>
  
  <pre><code> &lt;?xml version="1.0" encoding="UTF-8"?&gt;
   &lt;?import java.lang.*?&gt;
   &lt;?import java.util.*?&gt;
   &lt;?import javafx.scene.*?&gt;
   &lt;?import javafx.scene.control.*?&gt;
   &lt;?import javafx.scene.layout.*?&gt;
  
   &lt;AnchorPane fx:id="bp" prefHeight="443.0" prefWidth="563.0" xmlns="http://javafx.com/javafx/8" xmlns:fx="http://javafx.com/fxml/1" fx:controller="tableviewmodalbaseview.FXMLDocumentController" /&gt;
  </code></pre>
  
  <p>And the error as follows</p>
  
  <pre><code>Exception in Application start method
  java.lang.reflect.InvocationTargetException
  at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
  at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
  at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
  at java.lang.reflect.Method.invoke(Method.java:497)
  at com.sun.javafx.application.LauncherImpl.launchApplicationWithArgs(LauncherImpl.java:389)
  at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
  at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
  at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
  at java.lang.reflect.Method.invoke(Method.java:497)
  at com.sun.javafx.application.LauncherImpl.launchApplication(LauncherImpl.java:323)
  at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
  at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
  at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
  at java.lang.reflect.Method.invoke(Method.java:497)
  at sun.launcher.LauncherHelper$FXHelper.main(LauncherHelper.java:767)
  
  
  Caused by: java.lang.RuntimeException: Exception in Application start method
  at com.sun.javafx.application.LauncherImpl.launchApplication1(LauncherImpl.java:917)
  at com.sun.javafx.application.LauncherImpl.lambda$launchApplication$152(LauncherImpl.java:182)
  at com.sun.javafx.application.LauncherImpl$$Lambda$51/17398621.run(Unknown Source)
  at java.lang.Thread.run(Thread.java:745)
  
  
  Caused by: javafx.fxml.LoadException: 
      file:/C:/Users/aboosidhu/Documents/NetBeansProjects/TableViewModalBaseView/dist/run1705880335/TableViewModalBaseView.jar!/tableviewmodalbaseview/FXMLDocument.fxml
  
  at javafx.fxml.FXMLLoader.constructLoadException(FXMLLoader.java:2605)
  at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2583)
  at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2445)
  at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3218)
  at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3179)
  at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3152)
  at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3128)
  at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3108)
  at javafx.fxml.FXMLLoader.load(FXMLLoader.java:3101)
  at tableviewmodalbaseview.TableCellFactorySample.start(TableCellFactorySample.java:46)
  at com.sun.javafx.application.LauncherImpl.lambda$launchApplication1$159(LauncherImpl.java:863)
  at com.sun.javafx.application.LauncherImpl$$Lambda$54/31372366.run(Unknown Source)
  at com.sun.javafx.application.PlatformImpl.lambda$runAndWait$172(PlatformImpl.java:326)
  at com.sun.javafx.application.PlatformImpl$$Lambda$46/22256815.run(Unknown Source)
  at com.sun.javafx.application.PlatformImpl.lambda$null$170(PlatformImpl.java:295)
  at com.sun.javafx.application.PlatformImpl$$Lambda$49/23180581.run(Unknown Source)
  at java.security.AccessController.doPrivileged(Native Method)
  at com.sun.javafx.application.PlatformImpl.lambda$runLater$171(PlatformImpl.java:294)
  at com.sun.javafx.application.PlatformImpl$$Lambda$48/265996.run(Unknown Source)
  at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95)
  at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
  at com.sun.glass.ui.win.WinApplication.lambda$null$145(WinApplication.java:101)
  at com.sun.glass.ui.win.WinApplication$$Lambda$37/23703675.run(Unknown Source)
  ... 1 more
  
  
  
   Caused by: java.lang.NullPointerException
  at tableviewmodalbaseview.FXMLDocumentController.initialize(FXMLDocumentController.java:151)
  at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2552)
  ... 22 more
  </code></pre>
  
  <p>So can anyone help me to fix the error on my code.Any answer will be appreciated.</p>