No need complicate gestures, just tapping the buttons, it is simple.
From 4 inches cell phone to 10 inches tablet, 15 steps app contents scale are provided.
Selected text range(thus highlight-ed text range) is able to changed with arrow keys.
Most operation buttons are removal.
Undo / Redo buttons
Lower / upper case replacing buttons
Japanese full width / half width chars replacing buttons
Tab stop button
Japanese full width space button