Update xbus envelope : Convert messages smart button to object type

• This is not an odoo task, just an enhancement to ticket 2023-01952
• In order to display only messages related to the envoloppe

models/xbus_envelope.py

@@ -53,6 +53,16 @@
         for record in self:
             record.message_count = len(record.message_ids)
 
+    # Action to display only messages coming from this envelope
+    def action_open_message(self):
+        action = self.env["ir.actions.actions"]._for_xml_id(
+            "xbus_common.xbus_message_action"
+        )
+        action["context"] = {"default_envelope_id": self.id}  # for message creations
+        action["domain"] = [("envelope_id", "=", self.id)]
+
+        return action
+
     def init(self):
         super().init()
         self.env.cr.execute(