title: How to add the icon image into the CheckBoxTreeItem?
body: <p>I've problem with the TreeView component, It has the CheckBoxTreeItem to check enable or disable, it's very select and unselect with this reference ==> Using JavaFX UI Controls: Tree View | JavaFX 2 Tutorials and Documentation with Using Tree Cell Editors.
  This is the image with the tree view have CheckBoxTreeItem 
  (<a href="http://docs.oracle.com/javafx/2/ui_controls/img/tree-view-checkbox1.png" rel="nofollow">http://docs.oracle.com/javafx/2/ui_controls/img/tree-view-checkbox1.png</a>)</p>
  
  <p>At now, I want to add the icon image beside the CheckBoxTreeItem (Its mean that we have the icon image beside the checkbox).</p>
  
  <p>Could anyone help me this problem?</p>
  
  <p>I saw that when I set like that
  tree.setCellFactory(CheckBoxTreeCell.forTreeView());
  ==> It can not show the icon</p>
  
  <p>This is my coding</p>
  
  <pre><code>package sample;  
  import javafx.application.Application;  
  import javafx.fxml.FXMLLoader;  
  import javafx.scene.Node;  
  import javafx.scene.Parent;  
  import javafx.scene.Scene;  
  import javafx.scene.control.CheckBoxTreeItem;  
  import javafx.scene.control.TreeView;  
  import javafx.scene.control.cell.CheckBoxTreeCell;  
  import javafx.scene.image.Image;  
  import javafx.scene.image.ImageView;  
  import javafx.scene.layout.StackPane;  
  import javafx.stage.Stage;  
  public class Main extends Application {  
      @Override  
      public void start(Stage primaryStage) throws Exception{  
          primaryStage.setTitle("Tree View Sample");  
          Node graphic  = new ImageView(new Image("https://duke.kenai.com/iconSized/duke4.gif"));  
          CheckBoxTreeItem&lt;String&gt; rootItem =  
                  new CheckBoxTreeItem&lt;String&gt;("View Source Files", graphic);  
          rootItem.setExpanded(true);  
          final TreeView tree = new TreeView(rootItem);  
          tree.setEditable(true);  
          tree.setCellFactory(CheckBoxTreeCell.&lt;String&gt;forTreeView());  
          for (int i = 0; i &lt; 8; i++) {  
              final CheckBoxTreeItem&lt;String&gt; checkBoxTreeItem =  
                      new CheckBoxTreeItem&lt;String&gt;("Sample" + (i+1), graphic);  
              rootItem.getChildren().add(checkBoxTreeItem);  
          }  
          tree.setRoot(rootItem);  
          tree.setShowRoot(true);  
          StackPane root = new StackPane();  
          root.getChildren().add(tree);  
          primaryStage.setScene(new Scene(root, 300, 250));  
          primaryStage.show();  
      }  
      public static void main(String[] args) {  
          launch(args);  
      }  
  }  
  </code></pre>
  
  <p>Thanks 4 your reading.</p>
  
  <p>Tran Quoc Ung</p>