Endless windows

I dont really need a separate window for every chat - why not make it the imessage style? Otherwise I get a message - double click the LINE app icon - then I have to choose the chat on the list, double tap it and only THEN I get to see the chat. Does it sound convenient to you? Cz it sure is not. Please, make your app easier to use.

Solnceutrookean about LINE, v4.4.2