Hi Glottis,
I've a got a solution that solved completly the problem : buy another Glo

!
More seriously, I haven't got a H20 device but a Glo, so perhaps it's not the same thing with this device, but on the Glo you can set a
refesh rate for nightmode and maybe it's should be a workaround pending a fix

:
Modify the "refreshScreenPages" in your .bobo/nightmode.ini like this :
[nightmode]
refreshScreenPages = 6
Indeed, we can imagine that your present value is set to "0" and I believe refreshScreenPages = 0 totally disables the refresh (and it may explain the ghosting that you see).
Try and come back to tell us the result.
NB : sorry again for my very bad english.