add panel-region class to vbox

Author: tschie

display_information/control-annotation-sublayer-visibility/src/main/java/com/esri/samples/control_annotation_sublayer_visibility/ControlAnnotationSublayerVisibilitySample.java

@@ -74,6 +74,7 @@ public void start(Stage stage) {
 
       // create a control panel and label for the checkboxes
       VBox controlsVBox = new VBox(6);
+      controlsVBox.getStyleClass().add("panel-region");
       controlsVBox.setBackground(new Background(new BackgroundFill(Paint.valueOf("rgba(0,0,0,0.3)"), CornerRadii.EMPTY,
               Insets.EMPTY)));
       controlsVBox.setPadding(new Insets(10.0));