X11 6.9 issue -- option "ZAxisMapping" -- "4 5" vs "4 5 6 7"

[martinko]

hello list!

i've just upgraded X11 from 6.8.2 to 6.9.0 and run into the following issue:

[note that this was first noticed in seamonkey..]

if i scroll my mouse wheel too fast, i'm suddenly moving in history
instead of scrolling the page. one quick finger movement is enough to
trigger this. very annoying.

so it seems to me that the events are interpreted as horizontal 
movements. i have 1-wheel mouse of the following type, though:

kernel: ums0: Logitech USB-PS/2 Optical Mouse, rev 2.00/11.10, addr 2, 
iclass 3/1
kernel: ums0: 3 buttons and Z dir.

and i found out that the new option introduced in X11 6.9 broke it:

	Option	    "Protocol" "auto"
	Option	    "Device" "/dev/sysmouse"
	Option      "ZAxisMapping" "4 5"	# ++ 2005-01-18 mato
	#Option	    "ZAxisMapping" "4 5 6 7"	#!!!

the first version (3rd line) was added manually by me long time ago, 
while the 2nd version (4th line) was automatically generated by new X11 
with `Xorg -configure`.
since i reverted it from "4 5 6 7" back to "4 5" scrolling just works 
again like charm.

note that i'm running freebsd 6.1-rc, after just reinstalling all my
ports from scratch.

any thoughts or suggestions pls ??

cheers,

martin