title: Custom component does not appear JavaFX
body: <p>I cannot figure out why my custom Stackpane does not appear. I have exported it to scenebuilder and scenebuilder also does not show my items in stack pane. Also i set blue background and it worked. Everything went blue. When i include my fxml directly, it works correctly but not when i use custom component aproach. 
  I managed to get my button showing when it was not in pane. 
  Is this layout issue or am i missing something. </p>
  
  <pre><code>public class TestPane extends StackPane{
  
  public TestPane() {
  
      FXMLLoader fxmlLoader = new FXMLLoader(getClass().getResource(
              "/fxml/components/TestPane.fxml"));
  
      //Set controller fot opened dialogWindow
      fxmlLoader.setController(this);
  
      try {
          fxmlLoader.load();
      } catch (IOException exc) {
          System.out.println("Error: " + exc.toString());
      }
  }
  </code></pre>
  
  <p>TestPane</p>
  
  <pre><code>    &lt;StackPane 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"&gt;
  &lt;children&gt;
  &lt;Button mnemonicParsing="false" text="Button" /&gt;
  &lt;/children&gt;
  &lt;/StackPane&gt;
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/mXJYV.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/mXJYV.png" alt="TestPane in scenebuilder"></a></p>
  
  <p><a href="https://i.stack.imgur.com/xnWwB.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/xnWwB.png" alt="Testing testpane in empty scenebuilder"></a></p>