Can I have transparent application shortcut on desktop in folder view?
With Breeze dark theme I get blue frames around icons when I just hover over icon even without clicking. And it stays this way.
https://imgur.com/a/I6hB2
I want to have them completely transparent but preserve other elements (like panel) as in original theme.

What file should I edit?

Have you moved the mouse over the icons ?

I think that the blue frame is the selection box. There is a recent bug report: Bug 377348 - Folder view icon hold as selected when cursor pass over them - https://bugs.kde.org/show_bug.cgi?id=377348 .

Thank you for reference. I confirmed the bug. But anyway I want to permanently have fully transparent background of icons no matter what state they are. So my question is still valid regardless of the bug.

Edit:
The bug is fixed. But still when I hover on icon it is too much blue for me. I want to make it less blue or more transparent.
something like this (KDE 4)
https://imgur.com/a/YjEyZ

And second thing I want to change color of notification on Panel task manager when file is downloading in Breeze dark from green to blue. What file should I edit and what value?
https://imgur.com/a/wMWlY

Most definitely it was an annoying bug. As for the color of the icon frames, I agree it's too blue. Something more transparent or even a pale milky color as in Windows is preferable. The desktop grid and the icon frames are an issue that I'm always very interested in.