Version: (using KDE 4.0.83) OS: Linux The windows' titlebars and chrome (both of KDE and non-KDE apps) are always the colour of inactive titlebars, even when they are active. In other words, there is no visual distinction between active and inactive windows.
This is because you're using the oxygen kwin style. Please use the Ozone kwin style.
Marking as proper dupe...
*** This bug has been marked as a duplicate of 160117 ***
Thanks, Pino, I searched but the title of that bug was not such that I was able to identify mine as a dupe. I was concentrating on the keyword "colour".