This is a funny question:
I was clicking around, setting up how I wanted my KDE program menu to look and I somehow managed to do what the following snapshot shows:
(a Search bar, so all I have to do is type in what program I'm looking for and it highlights where it is in the menu.)
I don't remember how I got that feature enabled. I wanted to tell my son-in-law how to do this also but I just couldn't find where I clicked to enable it. Does anyone know?