So there is no more Nautilus Preferences menu in Quantal. There is a bug on this 999827. Apparently (from the bug report) "These items were moved into an application menu, but it appears that Unity is not correctly showing this menu with the normal menu"..."I am told indicator-application is responsible for this menu trickery. Leaving the nautilus task open as it looks like a nautilus bug to users." This bug report is not being updated. Any idea how to activate the single click mouse behaviour in the meantime?