Hi Norm, I was just thinking that if that was to work, it would only work if your application (file browser) had the icon display setting size set to 64pix, wouldn't it?
I think most of us in this discussion have been around long enough to know that all, or most, of our icons were at one time bitmaps but we changed them all (or at least the majority) over to svg. Not sure if that is relevant here or not.
Anyway I tried Norm's suggestion with the svg
and it instantly worked. All I did was close Dolphin and start Dolphin again. No restarting "Windows" I was expecting I might have to restart X, but no, I just restarted Dolphin (KDE file browser). Linux rules!
Before screen shot
after screen shot
the icon I used was the one Norm attached to his post.
I have been a bit slow posting this as I am trying to cook a marinated roast beef with assorted roast veggies...yum....and no its definitely not one of mine...
Kubuntu 18.04 64bit
Jim