private void updateIcon() {
    Node iconNode = icon.get();
    ObservableList<Node> children = controlBox.getChildren();
    children.remove(0);
    children.add(0, iconNode);
    iconNode.getStyleClass().add("tab-icon");
  }
Replaces the Icon when calling setModule().
workbenchfx-demo/src/main/java/com/dlsc/workbenchfx/demo/controls/CustomTabSkin.java