No. Look at the bottom of the f.lux window.

+1

On a dual-monitor setup I'm also getting this effect on the window without focus.

The following screengrab is not how it looks to the naked eye:
0_1547723850476_Screenshot 2019-01-17 at 11.08.59.png

When I opened the screengrab in an image editor the icon background is transparent with white icon.. actual appearance to the eye is black background white icon like this:
0_1547723888579_Screenshot 2019-01-17 at 11.08.59-edit.png

Usually this means you have two GPUs, and one of them isn't accepting color changes.

f.lux normally writes a color profile to handle this case - see information here:
https://justgetflux.com/news/2014/10/28/profile.html

Exactly what @TwoCables said.

@sierrafluxnoluv Call me clueless but how do I get into Flux to change the settings manually? Thank you. Gary

@terry Never mind. I just made Safari lie to your web site about my OS so it gave me the Snow Leopard Version, and that still runs on Mojave. I can see for myself those features do indeed exist in the older version. If this helps her. I'm sending you money, for sure!

We run applescript to adjust the dark theme every day. I am not sure how BetterTouchTool works, but we don't intentionally interact with it.