Does not ask to save if closing a modified document without export to PDF

Hello,

PDF Shuffler is a very nice program to handle with multiple PDF files to re-order them with thumbnail view.

Just there is a big missing feature : when I import some PDF and modify the original files - ie adding other documents, move / suppress pages... if I forget to save and export my new file as PDF and click on the close left button or on "File - Quit", PDF Shuffler just closes immediately without any warning, and all the modifications are lost.

Expected behavior is the same as all other softwares if possible : if I try closing a modified document without having saved, I'd like a window opening with the message "Save document XXXX modifications before closing" and buttons "Close without saving", "Cancel", "Save As".

Thanks in advance.