I am not a fan of Gnome default backgrounds but I do like the blue one with stripes (left). Anyway, if you are on Windows and you want to grub it, or if you are just curious about what are the backgrounds that Gnome 3.6 ships there you go..
I don’t know if all these backgrounds made by Gnome contributors for Gnome (I doubt and I didn’t check on it), -maybe “official” word isn’t quite correct- but this is what you’ll get in a genuine Gnome installation.
So these are the 18een Gnome Wallpapers
You will find them in Gnome Git Repo: http://git.gnome.org/browse/gnome-backgrounds/tree/backgrounds (click on plain). Everything is on high resolution, but I didn’t find the source files.
Gnome Photos is one of these applications that are suitable for new contributors to hack them. It is written in C and is still on early stages so there isn’t much code to read.
If you want to contribute:
Photos, like Documents, Music and Videos, is one of the core GNOME applications meant for find and reminding the user about her content. The internal architecture Photos is based on Documents — the document manager application for GNOME, because they share similar UI/UX patterns and objectives.
Points to remember while hacking on Photos:
+ Share the same set of widgets as Documents, or the other core GNOME applications, as much as possible.
+ Monitor changes in the Documents code base and clone them when relevant.
+ Follow the GNU coding style. To accomodate longer class and method names due to namespace prefixes, line lengths up to 120 characters are allowed.
happy hacking ;)