Code review comment for lp:~renatofilho/ubuntu-system-settings/symbolic-icon

I did not find any document about that. I remember to have one a long time ago when I was working on that but the designers that are working with me left canonical already;

What I can say is that: This was working before change the application name to the full icon path. You can confirm that by just using the icon name instead of the full path icon. It will "atomagically" find the symbolic icon and use that on the messaging menu (there is no need to explicitly specify the symbolic icon name when you use the only the icon name).
But as I said before this new property X-Ubuntu-SymbolicIcon was created to cover click app use case, and since system settings is using the full icon name it must specify the symbolic-icon-name.

And yes this is valid for all Apps that use the full icon name on desktop file.