10. The method of claim 9 , wherein the request for the addition of the certain conversation partner corresponds to an input of dragging and dropping the certain conversation partner to be added in the sub-chatting window.
9. The method of claim 1 , further comprising: selecting a certain conversation partner to be added if a request for an addition of the certain conversation partner is detected; extracting a dialog of the certain conversation partner to be added; and displaying the extracted dialog of the certain conversation partner to be added on the sub-chatting window.