Comment 4 for bug 87101

Two key questions here:

* Who deletes the temp file -- Mozilla or the OS?
* When is the file deleted -- after the user closes the 3rd party application,
or after Mozilla is closed?

If Mozilla deletes the file, or if the file is deleted only after Mozilla is
closed, then it should be possible to detect the changes, even if no explicit
flag is sent to Mozilla. In particular, either the timestamp or (on Win32) the
archive attribute can be used.

Once such a change is detected (after the 3rd part app is closed; since Mozilla
spawns that app, it should be able to detect that it was closed?) -- after such
a change is detected, Mozilla should pop up a dialog box offering the user to
save a copy (i.e., if the user approves, Mozilla should create the copy in a
location selected by the user; don't leave it as a mere "go save your file"
notification).

A special case is when the attachment was opened from a message in the Unsent
folder (see Bug 215394) -- here Mozilla should (also) offer to update the
unsent message with the new version of the attachment.

 - Tal