**Expected Behavior** Show cursor markers of participants in the editor. **Actual Behavior** The cursor marker of the participant which has left still shown.  **Steps to Reproduce** It shows sometimes 1. open a file as userA, 2. open a file as userB, 3. put the two users' cursor at the same position in each editor (type sth.) 4. close/leave one user's editor 5. open the same project file 6. extra cursor marker appears at the previous cursor position 