blacey wrote:The goal is to use as single, cross-platform document icon
I don't think that is possible since all 3 platforms have different guidelines regarding design however you could use the same base.
For OSX the guidelines are pretty stable and the theming only changes every decade or so, last change was Yoshemite.
Guidelines are specifying the use of multiple PNG files inside the ICNS with 1024x1024 being the largest one, nothing is written down about the use of text in the document icon all tough it seems most apps are using it. (leaving it away would make live simpler but on the other hand since OSX is hiding extensions for known file types it could be handy to put them in the icon after all)
https://developer.apple.com/library/mac ... 7-CH87-SW1
On GNU desktop guidelines are from freedesktop.org and are pretty clear, XPM, PNG or SVG may all be used however PNG is preferred.
Don't think I ever seen text on a freedesktop.org icon.
https://specifications.freedesktop.org/ ... atest.html
Windows are clean...