after last upgrade:
net-print/cups-1.3.7-r1
net-print/xfprint-4.4.2-r1
x11-libs/gtk+-2.12.9-r2
x11-libs/wxGTK-2.8.7.1-r1
gtk-engines-xfce-2.4.2
dev-python/pygtk-2.12.1-r2
gtk2-perl-1.145
dev-perl/gtk2-ex-formfactory-0.65-r1

after downgrade to try:
x11-libs/gtk+-2.12.9-r1
x11-libs/gtkglarea-1.99.0
dev-python/pygtk-2.12.0

------------------------------------
Portage 2.1.4.4 (default/linux/amd64/2008.0, gcc-4.1.2, glibc-2.6.1-r0, 2.6.24-gentoo-r8 x86_64)
=================================================================
System uname: 2.6.24-gentoo-r8 x86_64 AMD Turion(tm) 64 Mobile Technology ML-30
Timestamp of tree: Wed, 27 Aug 2008 14:45:01 +0000
app-shells/bash:     3.2_p33
dev-java/java-config: 1.3.7, 2.1.6
dev-lang/python:     2.5.2-r6
sys-apps/baselayout: 1.12.11.1
sys-apps/sandbox:    1.2.18.1-r2
sys-devel/autoconf:  2.13, 2.61-r2
sys-devel/automake:  1.4_p6, 1.5, 1.7.9-r1, 1.8.5-r3, 1.9.6-r2, 1.10.1
sys-devel/binutils:  2.18-r3
sys-devel/gcc-config: 1.4.0-r4
sys-devel/libtool:   1.5.26
virtual/os-headers:  2.6.23-r3
ACCEPT_KEYWORDS="amd64"
CBUILD="x86_64-pc-linux-gnu"
CFLAGS="-march=athlon64 -msse3 -O2 -pipe"
CHOST="x86_64-pc-linux-gnu"
CONFIG_PROTECT="/etc /usr/kde/3.5/env /usr/kde/3.5/share/config /usr/kde/3.5/shutdown /usr/share/config"
CONFIG_PROTECT_MASK="/etc/ca-certificates.conf /etc/env.d /etc/env.d/java/ /etc/fonts/fonts.conf /etc/gconf /etc/revdep-rebuild /etc/terminfo /etc/udev/rules.d"
CXXFLAGS="-march=athlon64 -msse3 -O2 -pipe"
DISTDIR="/usr/portage/distfiles"
FEATURES="distlocks metadata-transfer parallel-fetch sandbox sfperms strict unmerge-orphans userfetch"
GENTOO_MIRRORS="http://distfiles.gentoo.org"
LANG="it_IT.UTF-8"
LC_ALL="it_IT.UTF-8"
LDFLAGS="-Wl,-O1"
LINGUAS="it en"
MAKEOPTS="-j2"
PKGDIR="/usr/portage/packages"
PORTAGE_RSYNC_OPTS="--recursive --links --safe-links --perms --times --compress --force --whole-file --delete --stats --timeout=180 --exclude=/distfiles --exclude=/local --exclude=/packages"
PORTAGE_TMPDIR="/var/tmp"
PORTDIR="/usr/portage"
PORTDIR_OVERLAY="/usr/portage/local/layman/gentopia /usr/portage/local/layman/xfce /usr/portage/local/layman/mozilla /usr/portage/local/layman/sunrise /usr/local/portage"
SYNC="rsync://rsync.europe.gentoo.org/gentoo-portage"
USE="3dnow 3dnowext X a52 aac acl acpi alsa amd64 avi bash-completion berkdb bzip2 cairo cddb cdparanoia cdr cli cracklib crypt cups dbus dri dts dvd dvdnav dvdr dvdread ffmpeg firefox fortran gcj gdbm gif gpm gtk hal iconv isdnlog java javascript jpeg midi mmx mp3 mpeg mudflap multilib ncurses nls nptl nptlonly nsplugin ogg oggvorbis opengl openmp pam pcre pdf perl png pppd python qt3 qt3support qt4 readline reflection sdl session sox spell spl sse sse2 ssl startup-notification svg sysfs tcpd tiff truetype unicode usb vorbis wifi wmf xine xml xorg xscreensaver xv xvid zlib" ALSA_CARDS="ali5451 als4000 atiixp atiixp-modem bt87x ca0106 cmipci emu10k1x ens1370 ens1371 es1938 es1968 fm801 hda-intel intel8x0 intel8x0m maestro3 trident usb-audio via82xx via82xx-modem ymfpci" ALSA_PCM_PLUGINS="adpcm alaw asym copy dmix dshare dsnoop empty extplug file hooks iec958 ioplug ladspa lfloat linear meter mmap_emul mulaw multi null plug rate route share shm softvol" APACHE2_MODULES="actions alias auth_basic authn_alias authn_anon authn_dbm authn_default authn_file authz_dbm authz_default authz_groupfile authz_host authz_owner authz_user autoindex cache dav dav_fs dav_lock deflate dir disk_cache env expires ext_filter file_cache filter headers include info log_config logio mem_cache mime mime_magic negotiation rewrite setenvif speling status unique_id userdir usertrack vhost_alias" ELIBC="glibc" INPUT_DEVICES="keyboard mouse synaptics" KERNEL="linux" LCD_DEVICES="bayrad cfontz cfontz633 glk hd44780 lb216 lcdm001 mtxorb ncurses text" LINGUAS="it en" USERLAND="GNU" VIDEO_CARDS="fglrx"
Unset:  CPPFLAGS, CTARGET, EMERGE_DEFAULT_OPTS, FFLAGS, INSTALL_MASK, PORTAGE_COMPRESS, PORTAGE_COMPRESS_FLAGS, PORTAGE_RSYNC_EXTRA_OPTS