New answers tagged icons
I would think that SVG is preferred, because they are scalable to any size. This should also answer your second question. For other formats, there are a variety of sizes. I got this from my Ubuntu installation. Based on this, I'm guessing you should include 8, 16, 22, 24, 32, 48, and 256. 8.5M /usr/share/icons/gnome/256x256 32K ...
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