Remove unread marker when receiving proper read receipt

matrixgw_frontend/src/widgets/messages/MainMessagesWidget.tsx

@@ -118,6 +118,23 @@ function _MainMessageWidget(p: {
         return n;
       });
     }
+
+    // Remove unread message on left sidebar
+    if (
+      m.type === "ReceiptEvent" &&
+      m.receipts.find((r) => r.user === user.info.matrix_user_id) !== undefined
+    ) {
+      p.onRoomsListUpdate((r) => {
+        const n = [...r];
+        const idx = r.findIndex((el) => el.id === m.room_id);
+        if (idx)
+          n[idx] = {
+            ...n[idx],
+            number_unread_messages: 0,
+          };
+        return n;
+      });
+    }
   };
 
   return (