Can you please attach a screenshot?

I have already added the screenshot in the url of the bug.
I have also resolved the problem by selecting breeze-dark as GTK2 and GTK3 theme. It did not thought of it before since I thought that the KRDC was KDE app not Gtk

I cannot see an URL for a screenshot. Can you please attach it?

KRDC is a KDE application. Can you reproduce this issue with any other KDE application?

Created attachment 100016 [details]
krdc breeze dark problem

here is the url:
https://snag.gy/gC2HUB.jpg

and I have added it as an attachment.
I will test other apps for the issue and provide comments here

Thanks. Now I also can see the URL in bug metadata. ;)

I can reproduce the problem also on: Okular, KTorrent, k3b and KSnapshot file save dialog. I will attach some screenshots for them also
Kate, KCalc, Gwenview, digiKam, Amarok, KMail, etc. do not have this problem.

Created attachment 100017 [details]
k3b breeze dark problem

Created attachment 100018 [details]
ktorrent breeze dark problem

Created attachment 100019 [details]
okular breeze dark problem

One more thing that maybe helps:
When I select GTK2 theme Breeze-Dark the problem is fixed
The selection of GTK3 does not solve the problem

Neither Okular, k3b or ktorrent are affected by what gtk theme you use though... unless you have set the KDE themes to pick up the GTK theme - which looking at it seems unlikely. 

With the GTK theme there is a generation shift that happened quite recently (and may not have picked up) where GTK3 apps suddenly didn't work with the old GTK3 theme. But that seems like it's not whats happening at all (that glitch just messed with rightclick menu's being white-on-white). 

What happens when you set the entire destop via Look n Feel to "Breeze Dark" and then go to GTK theme, set that in turn to Breeze Dark (and Breeze Dark Icons) - then do the log-in-log-out dance?

Hi, Chiming in.
From the screenshots of k3b, ktorrent and okular, it does seem that Qt is set to use the QT-Gtk theme (which converts a gtk theme into a Qt theme), and then gtk set to use breeze (breeze-dark ?).
This configuration is not supported. 

I would recommand try to set the Qt theme to use breeze directly (and breeze-dark as a color theme). this should make (e.g.) okular, look like this: 

http://wstaw.org/m/2016/07/14/plasma-desktopDS8175.png

Which is fine

Sorry for the slow response. 

As I have stated above, if I set the theme from Look & Feel to breeze dark, the problem is  present, but it is fixed if I set also breeze dark to gtk2 setting. However I have retested the whole set breeze dark/ breeze light and login logout and the problem is present if I do not also set the gtk2 theme.

From the KDE point I do not know how to set Qt to follow Gtk theme, but if you can point me in the right direction I can test that.

I have forgot to mention that I have qt development environment and qt creator, so maybe that messes things up

I can't reproduce this. Is it still happening for you?

I have tested the issue now, and I can not reproduce it, I guess it was fixed during the years

Thanks!