add CMsgClientUIMode and enable chat_mode=2

steam/client/__init__.py

@@ -533,6 +533,8 @@ class SteamClient(CMClient, BuiltinBase):
         message.body.client_language = "english"
         message.body.should_remember_password = True
         message.body.supports_rate_limit_response = True
+        message.body.ui_mode = 0
+        message.body.chat_mode = 2
 
         if login_id is None:
             message.body.obfustucated_private_ip = ip_to_int(self.connection.local_address) ^ 0xF00DBAAD

steam/core/msg/__init__.py

@@ -23,6 +23,7 @@ cmsg_lookup_predefined = {
 #   EMsg.ClientEmailChange4: steammessages_clientserver_2_pb2.CMsgClientEmailChange,
 #   EMsg.ClientEmailChangeResponse4: steammessages_clientserver_2_pb2.CMsgClientEmailChangeResponse,
     EMsg.ClientLogonGameServer: steammessages_clientserver_login_pb2.CMsgClientLogon,
+    EMsg.ClientCurrentUIMode: steammessages_clientserver_2_pb2.CMsgClientUIMode,
 }
 
 cmsg_lookup = dict()