A dark theme is in the works for the next feature version. See attached screenshots how it will look.
We have no date set yet for this release but expect it during the spring. You are welcome to give it a try during the BETA testing that will be announced on our web site.
judging by those Screenshots, I really like what I see. Can't wait to finally have a dark theme for DBVis.
Hope it will be released sooner than later. :)