[FIX] mail: register thread window after append in DOM

Before this commit, we may have the following error:

`TypeError: Cannot read property 'html' of undefined`

This happened in the following scenario:

Terminology:
- in multi-tab environment, there is a master tab and slave tabs
- master tab fetches notifications from the server and forwards them
to slave tabs

State:
- 2 logged-in users: Michell & Marc
- Mitchell has open 2 browser tabs
- Mitchell has a pinned private conversation with Marc

Steps:
- Mitchell has focus on a slave tab
- Marc posts several messages to Mitchell in very quick succession

=> Mitchell gets crash error above.

This issue is caused by chat window being registered in mail manager
while it has not been mounted to DOM. On receiving 2nd new message,
it has to re-render chat window header in order to update displayed
unread counter. However, this fails due to chat window having no DOM
node yet.

This commit solves the issue by mounting chat window to DOM before
being registered in mail manager. That way, on receiving 2nd new
message, it does not trigger a re-render on chat window that
is about to be mounted to DOM, since it has not been registered yet.
Note that the displayed unread counter will be correct, because it
uses the up-to-date unread counter on mount.

Task-ID 2050108

closes odoo/odoo#35601

Signed-off-by: Martin Geubelle (mge) <mge@openerp.com>

0 files changed, 0 insertions, 0 deletions