FileChooser.showSaveDialog needs an owner window. In a JFXPanel I can only use scene.window (it wouldn't take a JFrame etc). This will show the dialog non-modal: the JFXPanel can be moved to the foreground, and the show call also is not blocking input to the JFXPanel and its window.

This is bad because the user could lose the save dialog behind their main window, or they could open multiple save dialogs, or they could select a file in a open dialog while the actual content to be saved is long gone (since input to that window is not blocked).