Save session files in going to background
Sometimes, app is terminated by system in going to background.
So if app is terminated, in the next launching, you saw recovery dialog but recovered file is not latest in the older version.
Because saving back up files for recovery (called saving session) is only one time in 15 minutes by default.
From this version, the app is saved session in going to background immediately and recover documents in the next launch automatically.
If the app is terminated or crashed, now you can get latest document without saving.
Enable to quit app by back key
Until the older version, it is necessary to press X button for quitting this app.
From this version, you can quit this app by pressing back key.
Fix for crashing in background
There is some problems of crashing in background.
This is fixed.