Closing a PDF after editing form content should show a dataloss warning and hint to "Save a copy"

Distribution

Mint 21.3

Package version

4.0.2

Frequency

Always

Bug description

When I want to fill a PDF form, then save it for sending per email, I need to save the filled form with "Save a copy" before sending. There is (potentially massive) dataloss risk in closing the filled form accidentally before saving, because one expects (similar to e.g. LibreOffice) to get a Save dialog when closing.

Steps to reproduce

Download and open https://web.archive.org/web/20180729222509if_/http://www.aloaha.com/wp-content/uploads/2016/07/statementidentify.pdf, then fill the "First Name" field. Now close the window, experiencing dataloss.

Expected behavior

When the window is closed after editing PDF form fields, a dialog box should pop up: "Some form fields were changed.", with answer buttons "Save a Copy ..." and "Don't save."

Additional information

No response

Reproduce the issue in Xreader using the linked PDF: fill the "First Name" field and close the window. Trace the close behavior and form-field change handling in the source, then verify that closing after edits presents "Some form fields were changed." with "Save a Copy ..." and "Don't save" options without losing the entered data.