split DC_EVENT_MSGS_NOTICED off DC_EVENT_MSGS_CHANGED

the new event can be used for updating the badge counter.
to get the old behaviour, implementations can just do the same on both events.

src/chat.rs

@@ -1795,10 +1795,7 @@ pub async fn marknoticed_chat(context: &Context, chat_id: ChatId) -> Result<(),
         )
         .await?;
 
-    context.emit_event(EventType::MsgsChanged {
-        chat_id: ChatId::new(0),
-        msg_id: MsgId::new(0),
-    });
+    context.emit_event(EventType::MsgsNoticed(chat_id));
 
     Ok(())
 }
@@ -1827,10 +1824,7 @@ pub async fn marknoticed_all_chats(context: &Context) -> Result<(), Error> {
         )
         .await?;
 
-    context.emit_event(EventType::MsgsChanged {
-        msg_id: MsgId::new(0),
-        chat_id: ChatId::new(0),
-    });
+    context.emit_event(EventType::MsgsNoticed(ChatId::new(0)));
 
     Ok(())
 }

src/contact.rs

@@ -16,7 +16,7 @@ use crate::error::{bail, ensure, format_err, Result};
 use crate::events::EventType;
 use crate::key::{DcKey, SignedPublicKey};
 use crate::login_param::LoginParam;
-use crate::message::{MessageState, MsgId};
+use crate::message::MessageState;
 use crate::mimeparser::AvatarAction;
 use crate::param::*;
 use crate::peerstate::*;
@@ -263,7 +263,7 @@ impl Contact {
     /// Mark all messages sent by the given contact
     /// as *noticed*.  See also dc_marknoticed_chat() and dc_markseen_msgs()
     ///
-    /// Calling this function usually results in the event `#DC_EVENT_MSGS_CHANGED`.
+    /// Calling this function usually results in the event `#DC_EVENT_MSGS_NOTICED`.
     pub async fn mark_noticed(context: &Context, id: u32) {
         if context
             .sql
@@ -274,10 +274,7 @@ impl Contact {
             .await
             .is_ok()
         {
-            context.emit_event(EventType::MsgsChanged {
-                chat_id: ChatId::new(0),
-                msg_id: MsgId::new(0),
-            });
+            context.emit_event(EventType::MsgsNoticed(ChatId::new(0)));
         }
     }
 

src/events.rs

@@ -186,6 +186,11 @@ pub enum EventType {
     #[strum(props(id = "2005"))]
     IncomingMsg { chat_id: ChatId, msg_id: MsgId },
 
+    /// Messages were seen or noticed.
+    /// If chat_id is 0, this affects multiple chats.
+    #[strum(props(id = "2008"))]
+    MsgsNoticed(ChatId),
+
     /// A single message is sent successfully. State changed from  DC_STATE_OUT_PENDING to
     /// DC_STATE_OUT_DELIVERED, see dc_msg_get_state().
     #[strum(props(id = "2010"))]

src/message.rs

@@ -1283,10 +1283,7 @@ pub async fn markseen_msgs(context: &Context, msg_ids: Vec<MsgId>) -> bool {
     }
 
     if send_event {
-        context.emit_event(EventType::MsgsChanged {
-            chat_id: ChatId::new(0),
-            msg_id: MsgId::new(0),
-        });
+        context.emit_event(EventType::MsgsNoticed(ChatId::new(0)));
     }
 
     true