When setting a graphic for a MenuButton the size of the imageView is ignored. Execute the test case below, the size of both images should be equal - in Java8b106 it works fine, in Java8b116 the MenuButton ignores the fitHeight setting for some reason. I don't know which release introduced the issue because I haven't tested all releases between the mentioned.

public class MenuButtonGraphicsTest extends Application
{
  public static void main(String[] args)
  {
    Application.launch(args);
  }

  @Override
  public void start(Stage stage)
  {
    System.err.println(System.getProperty("javafx.runtime.version"));
    Scene scene = new Scene(createContentPane(), 400, 300);
    stage.setScene(scene);
    stage.setTitle(getClass().getSimpleName());
    stage.show();
  }

  private Parent createContentPane()
  {
    Pane content = new FlowPane(10, 10);
    MenuButton menuButton = new MenuButton();
    ImageView imageView = new ImageView(getClass().getResource("/com/sun/javafx/scene/control/skin/modena/HTMLEditor-Background-Color-Black@2x.png").toExternalForm());
    imageView.setFitHeight(16);
    menuButton.setGraphic(imageView);
    content.getChildren().add(menuButton);

    ImageView imageView2 = new ImageView(getClass().getResource("/com/sun/javafx/scene/control/skin/modena/HTMLEditor-Background-Color-Black@2x.png").toExternalForm());
    imageView2.setFitHeight(16);
    content.getChildren().add(imageView2);
    
    return content;
  }
}