He's not forking the whole Gnome 3, just the shell so it looks more like Gnome 2. Keeping the backend untouched should keep the compatibility issues to a minimu

He's not forking the whole Gnome 3, just the shell so it looks more like Gnome 2. Keeping the backend untouched should keep the compatibility issues to a minimum and guarantee that libraries are up to date and no work is unnecessarily duplicated.