I have performed a bare metal netinstall of Ubuntu 12.04 64bit - only the very basic system, just to get the PC started. Next, I've installed packages lxde-core, xorg and lxdm to get a basic graphical environment.
Now, when trying to install package pidgin, a lot of extra packages are selected. Among them: gnome-session gnome-session-bin gnome-session-common gnome-session-fallback. My guess is that most of the others packages are dependencies of these ones.
As I had another virtual vmware installation of Ubuntu 12.04 32bit that was installed a while ago and then successfully dist-upgraded a number of times (with the package pidgin installed without the long list of extra packages) I've did a simple test: I've removed pidgin (& its dependencies - a short list) from this installation and tried to install again pidgin. I've got the same long list of extra packages.
The full output of "sudo apt-get install pidgin" follows:
user@pc:~$ sudo apt-get install pidgin
[sudo] password for user:
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following extra packages will be installed:
accountsservice alacarte apg appmenu-gtk appmenu-gtk3 appmenu-qt avahi-utils bamfdaemon bc brasero brasero-cdrkit brasero-common colord
compiz compiz-core compiz-gnome compiz-plugins-default compiz-plugins-main-default compizconfig-backend-gconf cups cups-client cups-common
cups-driver-gutenprint cups-filters cups-ppdc desktop-file-utils dvd+rw-tools evolution-data-server evolution-data-server-common
foomatic-db-compressed-ppds foomatic-db-engine foomatic-filters genisoimage geoclue geoclue-ubuntu-geoip ghostscript-cups
gir1.2-panelapplet-4.0 gnome-applets gnome-applets-data gnome-control-center gnome-control-center-data gnome-desktop3-data gnome-media
gnome-menus gnome-online-accounts gnome-panel gnome-panel-data gnome-session gnome-session-bin gnome-session-common gnome-session-fallback
gnome-settings-daemon gnome-system-monitor growisofs gstreamer0.10-gconf gstreamer0.10-nice hwdata indicator-applet
indicator-applet-complete indicator-application indicator-appmenu indicator-datetime indicator-messages indicator-power indicator-printers
indicator-session indicator-sound indicator-status-provider-mc5 indicator-status-provider-pidgin libaccountsservice0 libbamf3-0
libboost-serialization1.46.1 libbrasero-media3-1 libcamel-1.2-29 libcanberra-gtk-module libcanberra-gtk0 libcolord1 libcompizconfig0
libcupscgi1 libcupsfilters1 libcupsmime1 libcupsppdc1 libcurl3-nss libdbusmenu-qt2 libdecoration0 libebackend-1.2-1 libebook-1.2-12
libecal-1.2-10 libedata-book-1.2-11 libedata-cal-1.2-13 libedataserver-1.2-15 libedataserverui-3.0-1 libexempi3 libfarstream-0.1-0
libgdata-common libgdata13 libglew1.6 libglewmx1.6 libglib2.0-bin libgmime-2.4-2 libgnome-control-center1 libgnome-desktop-3-2
libgnome-media-profiles-3.0-0 libgnome-menu-3-0 libgnome-menu2 libgnomekbd-common libgnomekbd7 libgoa-1.0-0 libgssdp-1.0-3 libgtkspell0
libgucharmap-2-90-7 libgupnp-1.0-4 libgupnp-igd-1.0-4 libgutenprint2 libgweather-3-0 libgweather-common libhpmud0 libibus-1.0-0 libical0
libido3-0.1-0 libindicate-gtk3 libindicate5 libindicator-messages-status-provider1 libjson-glib-1.0-0 liblaunchpad-integration1
libmeanwhile1 libmetacity-private0 libmysqlclient18 libnice10 libnux-2.0-0 libnux-2.0-common liboauth0 libpackagekit-glib2-14
libpanel-applet-4-0 libperl5.14 libprotobuf7 libpurple-bin libpurple0 libqt4-dbus libqt4-declarative libqt4-network libqt4-script libqt4-sql
libqt4-sql-mysql libqt4-xml libqt4-xmlpatterns libqtcore4 libqtgui4 libquvi-scripts libquvi7 librest-0.7-0 libsensors4 libslp1 libsnmp-base
libsnmp15 libtimezonemap1 libtotem-plparser17 libunity-core-5.0-5 libunity-misc4 libupower-glib1 libwacom-common libwacom2 libwnck-3-0
libwnck-3-common libx86-1 libzeitgeist-1.0-1 libzephyr4 metacity metacity-common mousetweaks mysql-common nautilus nautilus-data nux-tools
pidgin-data pidgin-libnotify pm-utils poppler-utils printer-driver-gutenprint printer-driver-hpijs printer-driver-min12xxw
printer-driver-pnm2ppa python-aptdaemon.pkcompat python-cups python-cupshelpers python-gconf python-gmenu python-gnomekeyring python-libxml2
python-notify python-packagekit python-smbc python-zeitgeist qdbus smbclient ssl-cert system-config-printer-common
system-config-printer-gnome system-config-printer-udev ubuntu-docs ubuntu-system-service unity unity-asset-pool unity-common
unity-lens-applications unity-lens-files unity-lens-music unity-lens-video unity-scope-musicstores unity-scope-video-remote unity-services
upower vbetool wodim zeitgeist zeitgeist-core zeitgeist-datahub zenity zenity-common
Suggested packages:
vcdimager libdvdcss2 dvdauthor readom compizconfig-settings-manager gnome-themes cups-bsd hplip cups-pdf xpp cdrskin evolution
evolution-data-server-dbg printer-driver-hpcups printer-driver-foo2zjs printer-driver-splix printer-driver-m2300w printer-driver-pxljr
openprinting-ppds cjet printer-driver-c2050 printer-driver-ptouch printer-driver-c2esp foomatic-db-gutenprint cdrkit-doc tomboy
gnome-netstatus-applet deskbar-applet cpufrequtils epiphany-browser desktop-base gnome-screensaver lightdm gstreamer0.10-plugins-bad
gstreamer0.10-fluendo-mp3 gstreamer0.10-plugins-ugly cdrdao glew-utils gutenprint-locales tcl8.5 tk8.5 libqt4-declarative-folderlistmodel
libqt4-declarative-gestures libqt4-declarative-particles libqt4-declarative-shaders qt4-qmlviewer libqt4-dev qt4-qtconfig lm-sensors slpd
openslp-doc snmp-mibs-downloader gnome-themes-standard xdg-user-dirs eog totem mp3-decoder gnome-sushi wireless-tools ethtool radeontool
gutenprint-doc hpijs-ppds hplip-doc magicfilter apsfilter python-gnome2-doc cifs-utils openssl-blacklist
The following NEW packages will be installed:
accountsservice alacarte apg appmenu-gtk appmenu-gtk3 appmenu-qt avahi-utils bamfdaemon bc brasero brasero-cdrkit brasero-common colord
compiz compiz-core compiz-gnome compiz-plugins-default compiz-plugins-main-default compizconfig-backend-gconf cups cups-client cups-common
cups-driver-gutenprint cups-filters cups-ppdc desktop-file-utils dvd+rw-tools evolution-data-server evolution-data-server-common
foomatic-db-compressed-ppds foomatic-db-engine foomatic-filters genisoimage geoclue geoclue-ubuntu-geoip ghostscript-cups
gir1.2-panelapplet-4.0 gnome-applets gnome-applets-data gnome-control-center gnome-control-center-data gnome-desktop3-data gnome-media
gnome-menus gnome-online-accounts gnome-panel gnome-panel-data gnome-session gnome-session-bin gnome-session-common gnome-session-fallback
gnome-settings-daemon gnome-system-monitor growisofs gstreamer0.10-gconf gstreamer0.10-nice hwdata indicator-applet
indicator-applet-complete indicator-application indicator-appmenu indicator-datetime indicator-messages indicator-power indicator-printers
indicator-session indicator-sound indicator-status-provider-mc5 indicator-status-provider-pidgin libaccountsservice0 libbamf3-0
libboost-serialization1.46.1 libbrasero-media3-1 libcamel-1.2-29 libcanberra-gtk-module libcanberra-gtk0 libcolord1 libcompizconfig0
libcupscgi1 libcupsfilters1 libcupsmime1 libcupsppdc1 libcurl3-nss libdbusmenu-qt2 libdecoration0 libebackend-1.2-1 libebook-1.2-12
libecal-1.2-10 libedata-book-1.2-11 libedata-cal-1.2-13 libedataserver-1.2-15 libedataserverui-3.0-1 libexempi3 libfarstream-0.1-0
libgdata-common libgdata13 libglew1.6 libglewmx1.6 libglib2.0-bin libgmime-2.4-2 libgnome-control-center1 libgnome-desktop-3-2
libgnome-media-profiles-3.0-0 libgnome-menu-3-0 libgnome-menu2 libgnomekbd-common libgnomekbd7 libgoa-1.0-0 libgssdp-1.0-3 libgtkspell0
libgucharmap-2-90-7 libgupnp-1.0-4 libgupnp-igd-1.0-4 libgutenprint2 libgweather-3-0 libgweather-common libhpmud0 libibus-1.0-0 libical0
libido3-0.1-0 libindicate-gtk3 libindicate5 libindicator-messages-status-provider1 libjson-glib-1.0-0 liblaunchpad-integration1
libmeanwhile1 libmetacity-private0 libmysqlclient18 libnice10 libnux-2.0-0 libnux-2.0-common liboauth0 libpackagekit-glib2-14
libpanel-applet-4-0 libperl5.14 libprotobuf7 libpurple-bin libpurple0 libqt4-dbus libqt4-declarative libqt4-network libqt4-script libqt4-sql
libqt4-sql-mysql libqt4-xml libqt4-xmlpatterns libqtcore4 libqtgui4 libquvi-scripts libquvi7 librest-0.7-0 libsensors4 libslp1 libsnmp-base
libsnmp15 libtimezonemap1 libtotem-plparser17 libunity-core-5.0-5 libunity-misc4 libupower-glib1 libwacom-common libwacom2 libwnck-3-0
libwnck-3-common libx86-1 libzeitgeist-1.0-1 libzephyr4 metacity metacity-common mousetweaks mysql-common nautilus nautilus-data nux-tools
pidgin pidgin-data pidgin-libnotify pm-utils poppler-utils printer-driver-gutenprint printer-driver-hpijs printer-driver-min12xxw
printer-driver-pnm2ppa python-aptdaemon.pkcompat python-cups python-cupshelpers python-gconf python-gmenu python-gnomekeyring python-libxml2
python-notify python-packagekit python-smbc python-zeitgeist qdbus smbclient ssl-cert system-config-printer-common
system-config-printer-gnome system-config-printer-udev ubuntu-docs ubuntu-system-service unity unity-asset-pool unity-common
unity-lens-applications unity-lens-files unity-lens-music unity-lens-video unity-scope-musicstores unity-scope-video-remote unity-services
upower vbetool wodim zeitgeist zeitgeist-core zeitgeist-datahub zenity zenity-common
0 upgraded, 220 newly installed, 0 to remove and 0 not upgraded.
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Thank you for taking the time to report this issue and helping to make Ubuntu better. Examining the information you have given us, this does not appear to be a bug report so we are closing it and converting it to a question in the support tracker. We understand the difficulties you are facing, but it would make more sense to raise problems you are having in the support tracker at https:/