Odd mouse button behaviour

[Harald Hanche-Olsen]

+ Harald Hanche-Olsen <hanche at math.ntnu.no>:

> [Once in a while, my mouse button settings, as set with the xmodmap
>  line  pointer = 1 9 3 4 ...  , stop working, though xmodmap -pp
>  still reports the setting I had made. Rerunning xmodmap fixes it.]
> [...]
> I have no idea what triggers this, so I don't feel I have enough
>  data to write a PR.

Now I do have a notion: Leaving the office in the evening after
running xlock and then returning in the morning and unlocking triggers
it, AFAICT every time. (Just running xlock for a shorter time does
not.) So naturally I got curious, and noticed from the log file that
something appears to trigger a rescan of USB devices when I unlock my
xlock in the morning. But is it Xorg, or is it hald, or is something
else to blame?

Here is the latest dmesg output from that time
(I omit the messages concerning attached USB disks etc):

Unknown USB device: vendor 0x046d product 0xc408 bus uhub4
ums0: <Logitech USB Trackball, class 0/0, rev 1.10/14.00, addr 5> on uhub4
ums0: 5 buttons.
Unknown USB device: vendor 0x046d product 0xc016 bus uhub3
ums1: <Logitech Optical USB Mouse, class 0/0, rev 2.00/3.40, addr 6> on uhub3
ums1: 3 buttons and Z dir.

Also, Xorg.0.conf is modified at the same time. I don't know how many
of its trailing lines are from this morning, so here is a random
number of trailing lines:

(II) XINPUT: Adding extended input device "AT Keyboard" (type: KEYBOARD)
(II) config/hal: removing device USB Trackball
(II) UnloadModule: "mouse"
(II) config/hal: Adding input device USB Trackball
(**) USB Trackball: Device: "/dev/sysmouse"
(==) USB Trackball: Protocol: "Auto"
(**) USB Trackball: always reports core events
(**) Option "Device" "/dev/sysmouse"
(==) USB Trackball: Emulate3Buttons, Emulate3Timeout: 50
(**) USB Trackball: ZAxisMapping: buttons 4 and 5
(**) USB Trackball: Buttons: 9
(**) USB Trackball: Sensitivity: 1
(II) XINPUT: Adding extended input device "USB Trackball" (type: MOUSE)
(II) USB Trackball: SetupAuto: hw.iftype is 4, hw.model is 0
(II) USB Trackball: SetupAuto: protocol is SysMouse

- Harald