After CapsLock on - key "h", "j", "k", "l" - work as arrows. App work in backgound. For Quit - right button on System Tray app icon.
Add some keys: "D" - as PageDown, "U" - PageUp, "X" - Del, "A" - Home, "E" - end. "/" - send "Control+F".
When mode is on - icon in tray are red. When mode off - icon is green.