I would like to display a message onto the screen upon the button press. The message should not have any window and should be displayed at the center of the screen over any
You could create an HBox and center it with a transparent background color (-fx-background-color: transparent;) and in your initialize function, hide it. On a button press, you can show it and either give it a timer and hide it at the end of the timer, or put a small "x" in the top right or bottom, or wherever, with a setOnAction(event -> { myText.hide() }) kind of thing. Just a thought that maybe this got too complicated when all you wanted to do was display some text.