[FIX] mail: fix "New messages" separator and channel_seen behaviour

- channel_seen is now called even for own message and only when needed
- channel_seen is now called with a message_id which transfer the
  decision of what is seen to the client which makes more sense

task-2282235
task-2282248

closes odoo/odoo#57950

X-original-commit: 04edfa50ccea305050d017c4a1996e561bc7bd57
Signed-off-by: Sébastien Theys (seb) <seb@odoo.com>

1 files changed, 3 insertions, 1 deletions

diff --git a/addons/mail/static/src/components/thread_preview/thread_preview.js b/addons/mail/static/src/components/thread_preview/thread_preview.js
index 6e30005225c..0e5a226a5f2 100644
--- a/addons/mail/static/src/components/thread_preview/thread_preview.js
+++ b/addons/mail/static/src/components/thread_preview/thread_preview.js
@@ -108,7 +108,9 @@ class ThreadPreview extends Component {
      * @param {MouseEvent} ev
      */
     _onClickMarkAsRead(ev) {
-        this.thread.markAsSeen();
+        if (this.thread.lastMessage) {
+            this.thread.markAsSeen(this.thread.lastMessage.id);
+        }
     }
 
 }