Inky defaults to a "Quick Reply" when responding to an email, demonstrated in Using Quick Reply (Desktop). There is a text block for response. This "Type your reply..." is intended for minimal notation response, and once you hit <Enter>, the message will send.  If you wish to send a more detailed response, click "EXPAND" and a new window will open.

Hitting "EXPAND" allows for sentences and paragraphs.  

If you would like to have a window open you can move around independently select "OPEN IN WINDOW":

Inky gives you multiple options for efficient, effective interactions and conversations, and, if you need it, the flexibility to give detailed and comprehensive responses in your correspondence.