o autostart.sh não costuma estar criado por default. Para tal basta seres tu a criá-lo em "~/.config/openbox/autostart.sh" .
Não te preocupes que ele sabe ir buscá-lo.
* Add a basic but user-friendly "Find Files" utility. (Can be launched from command line, too) This can completely replace the simple find tool provided by GNOME.
* Fix folder handler problems previously interfering nautilus under GNOME.
* Rename the menu item showed in the system menu from "PCMan File Manager" to "File Manager" for better usability.