As title. Thanks.
Have you included Anna style icon in your project?
Now the question is, which tool can be used to convert a PNG file into SVG file that can be accept by Qt?
Boring to the heart. I spend 5 hours on this with nothing rewarded. OMG.
I've read that you can use png (instead svg) in your Qt app, as icon, too. (just give your_icon_name.png instead of .svg in your .pro file). The png should be 256x256 px