I found the reason for the failing of the default Pclos Ksplash boot screen.
The moving icons in the boot screen are not located on the center line, but are moved bellow the
600 limit of the 1024x600 netbook screen.
By modifying the file /usr/share/apps/ksplash/Themes/Default/1600x1200/description.txt
from (original contents):
SCALE ON
BACKGROUND_IMAGE 0 0 background.png
SCALE OFF
# the image is 390x234, make it centered, all icons need the same adjustment too
#IMAGE_REL CC 0 260 CC userlist.png
# these have their relative positions to the rectangle adjusted by -195,-117
# (i.e. half of the rectangle size)
# 3,32
ANIM_REL 1 CC -192 200 LT 30 icon1_anim.png 85 1
WAIT_STATE kded
# 69,32
ANIM_REL 2 CC -126 200 LT 30 icon2_anim.png 85 1
WAIT_STATE kcminit
# 135,32
ANIM_REL 3 CC -60 200 LT 29 icon3_anim.png 85 1
WAIT_STATE ksmserver
# 201,32
ANIM_REL 4 CC 6 200 LT 30 icon4_anim.png 85 1
WAIT_STATE wm
# 263,15
ANIM_REL 5 CC 68 158 LT 30 icon5_anim.png 85 1
WAIT_STATE desktop
WAIT_STATE ready
# show the icons fully right before the splash goes away
STOP_ANIM 1
IMAGE_REL CC -192 200 LT icon1.png
STOP_ANIM 2
IMAGE_REL CC -126 200 LT icon2.png
STOP_ANIM 3
IMAGE_REL CC -60 200 LT icon3.png
STOP_ANIM 4
IMAGE_REL CC 6 200 LT icon4.png
STOP_ANIM 5
IMAGE_REL CC 68 158 LT icon5.png
into (new contents):
SCALE ON
BACKGROUND_IMAGE 0 0 background.png
SCALE OFF
# the image is 390x234, make it centered, all icons need the same adjustment too
#IMAGE_REL CC 0 260 CC userlist.png
# these have their relative positions to the rectangle adjusted by -195,-117
# (i.e. half of the rectangle size)
# 3,32
ANIM_REL 1 CC -192 158 LT 30 icon1_anim.png 85 1
WAIT_STATE kded
# 69,32
ANIM_REL 2 CC -126 158 LT 30 icon2_anim.png 85 1
WAIT_STATE kcminit
# 135,32
ANIM_REL 3 CC -60 158 LT 29 icon3_anim.png 85 1
WAIT_STATE ksmserver
# 201,32
ANIM_REL 4 CC 6 158 LT 30 icon4_anim.png 85 1
WAIT_STATE wm
# 263,15
ANIM_REL 5 CC 68 120 LT 30 icon5_anim.png 85 1
WAIT_STATE desktop
WAIT_STATE ready
# show the icons fully right before the splash goes away
STOP_ANIM 1
IMAGE_REL CC -192 158 LT icon1.png
STOP_ANIM 2
IMAGE_REL CC -126 158 LT icon2.png
STOP_ANIM 3
IMAGE_REL CC -60 158 LT icon3.png
STOP_ANIM 4
IMAGE_REL CC 6 158 LT icon4.png
STOP_ANIM 5
IMAGE_REL CC 68 120 LT icon5.png
the icons are moved to the bottom limit of the netbook screen.
Differences are at lines with 'ANIM_REL...' (5x) and 'IMAGE_REL CC...' (5x).
Maybe this is a good reason to modify the default Pclos Ksplash boot screen, together with a better vga=... detection, in order to make it 100% suitable for a Netbook