Qt has some well known bugs about not being able to set QCombobox color..
In situations like this one, you cannot set the text to a light color
to contrast the dark background, and in the testing I did for the new
Linux Mint based live CD it looked terrible as it was.

This commit represent me officially giving up on trying to use a dark
background-color for QComboBox, I'm now going with a light color and
doing everything I can to make it blend with the remaining dark theme...