636617 - Dragging attachments from one message to a new one changes attachment order when sending

Status: NEW

(MailNews Core :: Composition, defect)

Description

[rsx11m]

Attachments added when composing a message are added top to bottom, regardless of their source. The user assumes that this order is retained, but it actually changes if one or more of these attachments as been dragged-and-dropped from another message.

Steps to reproduce:
1. Display a message with attachments;
2. compose a new message;
3. drag-and-drop an attachment from the message viewed to the new message;
4. use drag-and-drop from a folder or Attach > File to add another attachment;
5. repeat #3 and/or #4 for additional attachments;
6. remember order of attachments, then send or save as draft;
7. look at the sent or saved message, note that attachments are out of order:
   a. first, all attachments manually attached from a file are listed,
   b. then, all attachments dragged from other messages are attached.

The expectation is that the order of the attachments is retained regardless of their respective sources. I'm aware of bug 229224 to reorder attachments after they were attached, but this is different in that the displayed order is later modified when the message is actually assembled.

Tested on Windows and Linux, current trunk and branch builds.