... and I can't see any substitution in the packages that are gonna be installed simultaneously in this update session.

LXDE here.
Synaptic details:
fluxbox will be removed
libexo-0.3_0 will be removed
task-fluxbox will be removed
terminal will be removed
xfburn will be removed
exo (version 0.3.107-2pclos2010) will be upgraded to version 0.7.0-1pclos2012
libxfce4util (version 4.6.2-1pclos2010) will be upgraded to version 4.8.2-1pclos2011
libxfcegui4 (version 4.6.4-1pclos2010) will be upgraded to version 4.8.1-1pclos2012
thunar (version 1.0.2-3pclos2010) will be upgraded to version 1.3.0-1pclos2012
thunar-volman (version 0.3.80-3pclos2010) will be upgraded to version 0.6.0-1pclos2012
xfce4-panel (version 4.6.4-1pclos2010) will be upgraded to version 4.9.0-1pclos2012
xfce4-screenshooter (version 1.7.9-1pclos2010) will be upgraded to version 1.8.0-1pclos2012
xfconf (version 4.6.2-1pclos2010) will be upgraded to version 4.8.1-1pclos2012
OpenSP (version 1.5.2-3pclos2011) will be installed
dblatex (version 0.2.9-1pclos2010) will be installed
docbook-dtd44-xml (version 1.0-3pclos2010) will be installed
docbook-style-dsssl (version 1.79-5pclos2010) will be installed
docbook-utils (version 0.6.14-7pclos2010) will be installed
ghostscript-dvipdf (version 9.04-2pclos2011) will be installed
gtk-doc (version 1.18-1pclos2011) will be installed
help2man (version 1.38.1-1pclos2010) will be installed
jadetex (version 3.12-117pclos2007) will be installed
libatk1.0-devel (version 2.0.0-2pclos2011) will be installed
libcairo-devel (version 1.10.2-2pclos2011) will be installed
libexo-0.7_1 (version 0.7.0-1pclos2012) will be installed
libfontconfig-devel (version 2.8.0-1pclos2010) will be installed
libfreetype6-devel (version 2.4.3-2pclos2010) will be installed
libgarcon0 (version 0.1.9-1pclos2012) will be installed
libgdk_pixbuf2.0_0-devel (version 2.24.5-2pclos2011) will be installed
libgtk+2.0_0-devel (version 2.24.5-3pclos2011) will be installed
libopenjade0 (version 1.3.3-0.1pclos2010) will be installed
libpango1.0-devel (version 1.28.4-2pclos2011) will be installed
libpixman-devel (version 0.24.0-1pclos2011) will be installed
libpng-devel (version 1.2.43-1pclos2010) will be installed
libpthread-stubs (version 0.3-1pclos2010) will be installed
libsource-highlight3 (version 3.1.3-1pclos2010) will be installed
libx11-devel (version 1.4.3-1pclos2011) will be installed
libxau-devel (version 1.0.6-1pclos2011) will be installed
libxcb-devel (version 1.7-1pclos2011) will be installed
libxcomposite-devel (version 0.4.3-1pclos2011) will be installed
libxcursor-devel (version 1.1.12-1pclos2011) will be installed
libxdamage-devel (version 1.1.3-1pclos2011) will be installed
libxdmcp-devel (version 1.1.0-1pclos2011) will be installed
libxext-devel (version 1.2.0-2pclos2011) will be installed
libxfce4ui1_0 (version 4.8.1-1pclos2012) will be installed
libxfce4util-devel (version 4.8.2-1pclos2011) will be installed
libxfixes-devel (version 5.0-1pclos2011) will be installed
libxft-devel (version 2.2.0-1pclos2011) will be installed
libxi-devel (version 1.4.2-1pclos2011) will be installed
libxinerama-devel (version 1.1.1-2pclos2011) will be installed
libxrandr2-devel (version 1.3.2-1pclos2011) will be installed
libxrender-devel (version 0.9.6-1pclos2011) will be installed
openjade (version 1.3.3-0.1pclos2010) will be installed
pango-doc (version 1.28.4-2pclos2011) will be installed
perl-SGMLSpm (version 1.03ii-10pclos2009) will be installed
source-highlight (version 3.1.3-1pclos2010) will be installed
tetex-context (version 3.0-19pclos2007) will be installed
tetex-dvips (version 3.0-19pclos2007) will be installed
tetex-latex (version 3.0-19pclos2007) will be installed
thunar-vfs (version 1.2.0-1pclos2012) will be installed
transfig (version 3.2.5a-1pclos2010) will be installed
x11-proto-devel (version 7.6-4pclos2011) will be installed
xfce4-dev-tools (version 4.9.0-1pclos2011) will be installed
xfce4-panel-devel (version 4.9.0-1pclos2012) will be installed
xmltex (version 1.9-65pclos2007) will be installed
xsltproc (version 1.1.26-2pclos2010) will be installed
Is it OK and should I proceed with the updates?
Thanks for attention
