Why are Dark Themes always like this?

[Jason]

Changed to Breeze Dark in Linux Mint 18.3 on the KDE Desktop. It's probably just because it's not a KDE application (it's Foxit Reader) but this really sucks. Not really looking for a solution - just complaining because I see this happen a lot with dark themes. Switched back to regular Breeze theme and it is fine (after closing and restarting the application).

[fox]

I have observed the same, and this has kept me clear of dark themes. I think that the problem is independent of desktop environment. I have noticed this on both gnome and Unity.

[Jason]

Yeah, I have as well. I think it's when you are using an application that isn't native to the environment (KDE apps in KDE, Gnome/GTK apps in Gnome). Or maybe they're just badly coded themes but you'd think one that was included with a distro would have been tested for this.