How to add Close button in the Summary Slide

Hi, 

I'm just wondering if anyone has had a chance to add a "Close" or "Submit" button in the default Summary slide of H5P to trigger a Close the Window command. I've received feedback from one of the lecturers who agreed to deploy interactive H5P quizzes to his courses. He said that it would be helpful to provide students some cues what to do next after completing a formative quiz. For instance, if a student achieves 100% or a perfect score, we want to add instruction in the Summary slide that reads as "Click the Submit button to submit this assessment to your lecturer and close this window." However, the Summary slide isn't customisable to that extent.   

At this point, we can only enable the Show Solution and Retry button in the Summary page. While Show Solution will prompt the user to review his responses to each question and the correct answer, the Retry button will create another record of attempt in the H5P Report and in the LMS (Blackboard Learn in our case). For the interactive quizzes set to capture and show the Last Attempt in the Blackboard Learn Grade Centre, this scenario might lead to the lecturer missing the perfect score because it was overridden by a new attempt triggered when the student clicked on the Retry button in the Summary slide. 

In a gist, a Close Window function in the Summary slide will have more impact in prompting students to wrap up their attempt instead having to rely on them intuitively clicking on the close/cross mark button of the window. 

Your advice will be much appreciated.