How to avoid the appearance of the prompt when leaving the page
When the web page is refreshed or when you close the web document without saving it, the following message will appear:
"Are you sure you want to navigate away from this page. You are editing the document. Press OK to continue, or cancel to stay on the current page."
In order to disable this mesage, open Domino Designer and go to "SwAttachmentsWeb" subform. In "JS Header" section of the subform replace the value of SwSkipClosePrompt to 1:
That way this message will be disabled.