how to change background colour for photo presenter?

Hey People
im trying out the trail of photo presenter
but cant find out how to change the background colour
how do you do this?
or is this only possible in the paid vision.
what to make sure you can before i buy it.

with the stack theme

The stack theme don’t support a custom background color in the current version (4.1.6) I am afraid. I take this as a feature request.