An alternate approach to develop a Debian Openbox desktop is to start with an lxde desktop. The lxde desktop is basically openbox with a sessions manager (lxsession) and a panel (lxpanel). There are no real advantages to start with a Debian LXDE distribution in my eyes, except if you already have an LXDE operating system installed, then you can easily just modify it to be the openbox system. In Debian Linux Openbox Guide, we showed how to develop a sophisticated Openbox desktop starting from the Sparky Linux Openbox (no codecs) base distro, which is based upon Debian Testing. As far as I know, this is the only Debian Testing pure openbox distro, and there are only 3 or 4 other reasonable ones based upon Debian Stable. So the choice starting with just Openbox is quite limited, and so starting from an LXDE distribution might be helpful to some.

Here, we will show how to develop a sophisticated Openbox desktop starting with Sparky Linux LXDE, specifically, Sparky Lxde 4.5.2x86_64. The following tables shows the differences in the starting points between the Sparky base Openbox and the Sparky Lxde.

LXDE Packages in Sparky LXDE not Completely in Sparky Openbox-Base
lxde-corepcmanfm, lxpanel, openbox, lxde-common, desktop-file-utils, xscreensaver
lxde-commonconfiguration data, libunique-1.0-0, lxsession
lxsessionlxsession-data, lxsession-logout
lxpanellxpanel-data, lxkeybinder0
openbox-lxde-sessionlxsession, openbox, lxde-screenlock.desktop file, configuration files

To get rid of the unnecessary LXDE desktop components, boot into the openbox-session. The display manager, lightdm, offers you a choice when the password window is open. Click the appropriate icon in the upper panel to get a drop-down box and put a tick in the openbox box. That will boot you into an openbox-session.

While booted into an Openbox session, uninstall lxde-core and lxde-common, which are just meta-packages, whose removal will not affect anything else:
        sudo apt-get remove lxde-core lxde-common .
        sudo apt-get remove openbox-lxde-session
        sudo apt-get remove lxsession lxsession-default-apps lxsession-edit .
If you are not going to keep lxpanel, then remove it as well:
        sudo apt-get remove lxpanel lxpanel-data .

In order to guarantee a menu in the next boot, you should immediately (before rebooting) install and configure a replacement panel (see, for example, fbpanel), and put a tick in the first box ("Show menus") in the "Advanced Section" of "Desktop Preferences":
        pcmanfm --desktop-pref .

Desirable Packages in Sparky LXDE not in Sparky Openbox-Base
Bit-torrent packagetransmission; transmission-common; transmission-gtk
media packageffmpeg; x264; x265
Java packageicedtea-8-plugin:amd64; icedtea-netx:amd64; icedtea-netx-common; icedtea-plugin 1.6.2-3; java-common; javascript-common; openjdk-8-jre:amd64; openjdk-8-jre-headless:amd64
rpm packagedebugedit; rpm; rpm-common; rpm2cpio
vlc packagevlc; vlc-bin; vlc-data; vlc-l10n; vlc-plugin-base:amd64; vlc-plugin-notify:amd64; vlc-plugin-qt:amd64; vlc-plugin-video-output:amd64; browser-plugin-vlc
wine64 packagewine64; winetricks
apt-xapian-indexmaintenance and search tools for a Xapian index of Debian packages
ca-certificates-javacommon CA certificates (JKS keystore)
camoramagnome utility to view and save images from a webcam
firefox-esrMozilla Firefox web browser - Extended Support Release (ESR)
florenceextensible and scalable virtual keyboard for X
gpointing-device-settingsmouse configuration tool
locatemaintain and query an index of a directory tree
lxappearanceLXDE GTK+ theme switcher
lxappearance-obconfLXDE GTK+ theme switcher (plugin)
parcellitelightweight GTK+ clipboard manager
lxappearanceLXDE GTK+ theme switcher
lxappearance-obconfLXDE GTK+ theme switcher (plugin)
parcellitelightweight GTK+ clipboard manager
xfburncd-dvd burner
Probably Keepers in Sparky LXDE not in Sparky Openbox-Base
apt-show-versionslists available package versions with distribution
bluemangraphical bluetooth manager
bluez-obexdbluez obex daemon
broadcom-sta-common, broadcom-sta-sourceBroadcom STA Wireless driver files
cabextractopens microsoft .cab files
compton, sparky-comptoncompositor for X11
disk-managergraphical filesystem configurator
ddmgui to install proprietory drivers
extlinuxcollection of bootloaders
fonts-crosextra-caladea, fonts-crosextra-carlitoSans-serif font metric-compatible with Cambria font
galculatorsimple calculator (hard to remove without installing big crap)
gnuplot, gnuplot-data, gnuplot-qt, aglfncommand-line driven interactive plotting program
gpointing-device-settingsconfiguration tool for pointing devices
gucharmap, libgucharmapunicode character picker and font browser
hardinfodisplays system information
libreoffice, coinor-*, lp-solve, unolibs3, urecomplete office suite (large - 482MB)
lxde-icon-themeLXDE standard icon theme
lxhotkey-core, lxhotkey-gtklightweight global keyboard shortcuts configurator
lxmedLXDE menu editor
minissdpdkeep memory of all UPnP devices
nvidia-detectNVIDIA GPU detection utility
NVIDIA GPU detection utilityNVIDIA GPU detection utility
ocl-icd-libopencl1:amd64Generic OpenCL ICD Loader
pkg-config, gstreamer1.0-toolsmanage compile and link flags for libraries
pmountmount removable devices as normal user
psutilsPostScript document handling utilities
recordmydesktop, gtk-recordmydesktopcaptures audio-video data of a Linux desktop session
sparky-fontsettool to configure fonts
sparky-usb-formattertool to format a usb drive
sparky-xdftool to show didk usage via df-command
traceroutetraces the route taken by packets over an IPv4/IPv6 network
usermodegraphical tools for certain user account management tasks
xinitX server initialisation tool
yelp, yelp-xsl, libyelp0help browser for gnome
Removable Packages in Sparky LXDE not in Sparky Openbox-Base
audacious, audacious-plugins:amd64, audacious-plugins:data, libaudcore4, libaudtag3, libaudgui4 audio player (8189kb)
bisonYACC-compatible parser generator (2110kb)
cryptsetup-bindisk encryption support (1060kb)
dkmsdynamic kernel module support framework (289kb)
evince, evince-commonpdf viewer (13.6mb)
flex, libfl-devlexical analyzer generator (1334kb)
gnome-desktop3-data, libgnome-desktop-3-12 common files for gnome desktop apps (3251kb)
gscreenshotsimple screenshooter (116kb)
hexchat, hexchat-common, hexchat-perl, hexchat-plugins, hexchat-python3IRC client (5529kb)
module-assistantmodule package creation tool (399kb)
pidgin, pidgin-data, pidgin-lastfm, pidgin-microblog, pidgin-musictracker, pidgin-twitter, libpurple-bin, libpurple0messaging client (34.1mb)
thunderbird, calendar-google-provider, lightning, iceowl-extension, icedovemail/news client (91.6MB)
radiotrayonline radio streaming player (589)
tcl, tcl8.6, tk, tk8.6, blt, python-tk, tk8.6-blt2.5tool command language (2447kb)
ttf-liberationdummy package (38.9kb)
usermodegraphical tools: userinfo, usermount, userpasswd (1183kb)
x11-session-utils, xorg, x11-xfs-utils, xorg-docs-core, task-desktopX session utilities (2652kb)
xserver-xephyrnested X server (4603kb)
sparky-center-lxde, sparky-autostart, "-conkeyset, "-keyboard, "-locales, "-timedateset, "-users, libfm-tools, console-setup (1600kb)

To achieve the desktop described in Debian Linux Openbox Guide, a user will need to install (as desired) the applications in the following table.

Packages to Add to Upgrade the System
arandrvisual front end for XRandR (328kb)
catfishfile searching tool (427kb)
filezillafull-featured FTP client with an easy-to-use GUI (17.3mb)
gaiksaurusgraphical interface to the Aiksaurus English language thesaurus (708kb)
geanybest text editor with syntax highlighting, html viewing and many plugins (10.7mb)
grabcprogram to determine the color by clicking on a pixel on the screen (28kb)
jqchanges the data format that you have into the one that you want (1157kb)
lamemp3 encoder (597kb)
libdvd-pkgprovides libraries that are needed for playing video DVDs (79kb)
miragelean, clean image viewer with some editing powers (2022kb)
mpvmovie player based on MPlayer (26mb)
obmenu-generatordynamical openbox menu generator (6469kb)
ogmriprips and encodes video dvd's (104mb)
openbox-menuprovides a dynamic menu listing of installed applications (41kb)
speedcrunchhigh precision and high speed calculator (5514kb)
streamripperrecords online radio-streams (187kb)
skypeonline video and audio messager
transcodeencodes video/audio streams extracted from dvd's (9692kb)
wavemonwireless device monitor (126kb)
xdotoolprogram to simulate mouse and keyboard activity (204kb)
xournalpdf reader and editor (1625kb)
vobcopyCopies dvd .vob files to harddisk and merges them into file(s) (99.2kb)
youtube-dldownloads videos from and other sites (5072kb)
9menuprogram that allows creation of a menu, where each menu item will run a command (43kb)
aisleriotif you have a slow internet (24.4mb)

All that remains is to configure as described in Debian Linux Openbox Guide; given that most of the applications mentioned there are already installed, provided you followed the above remove-keep guideline..