Good question. The link you quoted wasn't too clear, I agree.
This is what I tried. I'll test it later.


First I followed Texstar's suggestion from the above thread;
"If you are using the KDE desktop it is set in the configure your desktop -> Workspace Appearance -> Default Applications."
In the foreground is the Configure your desktop -> Workspace Appearance -> Default Applications window.
I got the command from KMenu editor-- see background window --
Give that a try. I will too.
p.s. You are using google-chrome-stable, rt?