api to get tray icon panel foreground color?

[Andriy Rysin]

In regards to https://bugs.kde.org/show_bug.cgi?id=266434
I've added a halo as suggested before and then had to increase its 
radius but it's still not a perfect solution for some themes. To provide 
reliable text in tray indicator needs to know suggested foreground 
color. Or background color but that might not work well if image is used 
for background.

So the question is what's the API to get suggested tray foreground color?

Thanks
Andriy