Kobo has released another firmware update for Mark 3, Mark 4, Mark 5 and Mark 6 devices.
Mark 6:
Mark 6 4.3.8842
Mark 5:
Mark 5 4.3.8842
Mark 4:
Mark 4 4.3.8842
Mark 3:
Mark 3 4.3.8842
The major change seems to be the home screen (for higher res devices), series sort in Library view, brightness level now changes by 1%, etc.
The usual very uninformative Kobo release notes: Your ereader software has been upgraded. DUH!!
Have fun!