public class FXTest extends Application {

public static void main(String[] args) {
launch(args);
}

@Override
public void start(final Stage primaryStage) throws Exception {
final Tooltip t = new Tooltip();
VBox box = new VBox();
box.getChildren().add(new Label("Hello"));
box.getChildren().add(new Label("World!"));
t.setGraphic(box);

Button b = new Button("Open Tooltip");
b.setOnAction(new EventHandler<ActionEvent>() {

@Override
public void handle(ActionEvent event) {
t.show(primaryStage);
}
});

Scene s = new Scene(b,400,400);
primaryStage.setScene(s);
primaryStage.show();
}

}

Run this sample and notice that:
a) the text is black on black
b) you'll receive CSS-Errors like

Jän 04, 2014 2:14:17 PM javafx.scene.CssStyleHelper calculateValue
WARNING: Could not resolve '-fx-text-background-color' while resolving lookups for '-fx-text-fill' from rule '*.label' in stylesheet jar:file:/Library/Java/JavaVirtualMachines/jdk1.8.0.jdk/Contents/Home/jre/lib/ext/jfxrt.jar!/com/sun/javafx/scene/control/skin/modena/modena.bss
Jän 04, 2014 2:14:17 PM javafx.scene.CssStyleHelper calculateValue
WARNING: Could not resolve '-fx-text-background-color' while resolving lookups for '-fx-text-fill' from rule '*.label' in stylesheet jar:file:/Library/Java/JavaVirtualMachines/jdk1.8.0.jdk/Contents/Home/jre/lib/ext/jfxrt.jar!/com/sun/javafx/scene/control/skin/modena/modena.bss
Jän 04, 2014 2:14:17 PM javafx.scene.CssStyleHelper calculateValue
WARNING: Could not resolve '-fx-text-background-color' while resolving lookups for '-fx-text-fill' from rule '*.label' in stylesheet jar:file:/Library/Java/JavaVirtualMachines/jdk1.8.0.jdk/Contents/Home/jre/lib/ext/jfxrt.jar!/com/sun/javafx/scene/control/skin/modena/modena.bss
Jän 04, 2014 2:14:17 PM javafx.scene.CssStyleHelper calculateValue
WARNING: Could not resolve '-fx-text-background-color' while resolving lookups for '-fx-text-fill' from rule '*.label' in stylesheet jar:file:/Library/Java/JavaVirtualMachines/jdk1.8.0.jdk/Contents/Home/jre/lib/ext/jfxrt.jar!/com/sun/javafx/scene/control/skin/modena/modena.bss
Jän 04, 2014 2:14:17 PM javafx.scene.CssStyleHelper calculateValue
WARNING: Could not resolve '-fx-text-background-color' while resolving lookups for '-fx-text-fill' from rule '*.label' in stylesheet jar:file:/Library/Java/JavaVirtualMachines/jdk1.8.0.jdk/Contents/Home/jre/lib/ext/jfxrt.jar!/com/sun/javafx/scene/control/skin/modena/modena.bss
Jän 04, 2014 2:14:17 PM javafx.scene.CssStyleHelper calculateValue
WARNING: Could not resolve '-fx-text-background-color' while resolving lookups for '-fx-text-fill' from rule '*.label' in stylesheet jar:file:/Library/Java/JavaVirtualMachines/jdk1.8.0.jdk/Contents/Home/jre/lib/ext/jfxrt.jar!/com/sun/javafx/scene/control/skin/modena/modena.bss