Instead of sleeping the thread, use a PauseTransition and load your new scene after the pause has finished.
createNewProject.setOnAction(event -> {
statusText.setText("Please wait...");
PauseTransition pause = new PauseTransition(
Duration.seconds(1),
);
pause.setOnFinished(event -> {
Parent root = FXMLLoader.load(
getClass().getResource(
"/view/scene/configure/NewProjectConfigureScene.fxml"
)
);
Scene scene = new Scene(root);
stage.setTitle("Configure New Project Settings");
stage.setScene(scene);
stage.sizeToScene();
});
pause.play();
});
The above code assumes you have just a single stage, so you resize your “Welcome” stage to become the “Configure New Project Settings” stage.