Is your feature request related to a problem? Please describe.
I would like to allow my app to feel native on KDE environments as much as possible. Therefore I would like to use icons from the system. Unfortunately, the QIcon::fromTheme method is not implemented

Describe the solution you'd like
An implementation of this method. For platforms which cannot support this, the function should simply inherit Qt's default behaviour of nothing.

Describe alternatives you've considered
So far, the only real alternatives are implementing the function myself or simply bundling icons, either as SVGs or through font icons.