For unity environment, I know it is /usr/share/pixmaps/flags + change setting org.gnome.libgnomekbd.indicator to true, which is totally successful. But for Gnome-shell ,both default and classic, ...
In Nautilus tree-view, pressing * (asterisk) expands the selected directory structure by ONE level. Pressing * again will expand the structure by one more level. ...etc, etc, untl all levels are ...