Other GTK apps have hints white text over black background, is the background color hardcoded? 
Arch (Antergos) KDE Plasma geany 1.31 (kompilacja: Jul 19 2017GTK 2.24.31, GLib 2.52.3)
Are you sure you're not using a GTK+3 build of Geany? I had this problem as well with KDE but I thought it was only when using GTK+3 Geany, not GTK+ 2.
No its not hard coded, it follows the GTK theme. Perhaps @codebrainz KDE distro didn't put much effort into the GTK themes after GTK3 when all the tools to translate KDE themes to GTK2 would have broken.
Add:
``` .tooltip { background-color: #00ff00; } ```
to `~/.config/gtk-3.0/gtk.css` and get minty green.
Closed #1651.
Okey ... that didn't help, but i did found that if I run geany from terminal it has this bad background, but if I run from start menu or krunner it loads and it get correctly black background.
Thanks for your help, so i need to look into theme and probably hit plasma team.
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