After posting that stuff before I discovered that you do need 'xhost local:' in a startup script in addition to the other hacks. Didn't remember to update the wiki.i'm a bit puzzled... all seems ok but it doesn't happen!
grub seems ok:
GRUB_CMDLINE_LINUX="acpi_osi=Linux acpi_backlight=vendor acpi_skip_timer nomodeset video=uvesafb:mode_option=1024x600-24,mtrr=3,scroll=ywrap pci=nocrs mem=896mb"
/etc/acpi/events/asus-rorate-t91 is created with 0000007b. a /etc/acpi/events/asus-rorate is already present with 0000009b.
the silver butter is firing the rotatescreen.sh : the date >> /tmp/rotate.org test works wherever i put it, i've also checked the /var/lib/acpi-support/screen-rotation file after pressing the button and it works well too, but the screen doesn't move any pixel!
also, from a terminal, the script /etc/acpi/rotatescreen.sh rotates screen as expected.
all seems ok but the /usr/bin/xrandr -o $NEW_ROTATION seems doing nothing when i press that button !!
some additionnal remarks:
when i put both events files (asus-rotate & asus-rotate-t91) to 0000007b or to 0000009b the results are the same (the rotate file fires).
dmsg has a hidden error message when the button is held pushed: unknown key ea (windows use this action to rotate). yeah! i'm glad to contribute