openbox-3.4.2 installs: /usr/share/doc/openbox: AUTHORS COMPLIANCE menu.xsd rc.xsd xbm CHANGELOG COPYING rc-mouse-focus.xml README /usr/share/doc/openbox-3.4.2: ABOUT-NLS.bz2 AUTHORS.bz2 CHANGELOG.bz2 COMPLIANCE.bz2 README.bz2 --docdir="/usr/share/doc/${PF}" to the econf fixes it for me.
Your fix seems to work fine; thanks for the bug. It should be fixed now.