Create

Hitting the add button will reveal a menu where you can choose if you want to insert a duplicate of the current selected frame, or a blank one.

Blank frames will have the first layer transparent if the project is also transparent, otherwise, blank frames will have the first layer the same color as the current selected secondary color.

Duplicates will duplicate all the layers of the current selected frame.

All new frames are inserted on the next position of the current selected frame.