Oh I found the answer here: https://github.com/adaptlearning/adapt_framework/issues/1957

var promptObject = {
    title: "Leaving so soon?",
    body: "Looks like you're trying to leave this page, yet you haven't completed all the learning. Would you like to stay on this page and complete it?",
    _prompts:[
        {
            promptText: "Yes",
            _callbackEvent: "pageLevelProgress:stayOnPage",
        },
        {
            promptText: "No",
            _callbackEvent: "pageLevelProgress:leavePage"
        }
    ],
    _showIcon: true,
    _classes: 'notify-button-centered'


}