synaptics should allow runtime configuration (eg. Option SHMConfig on)

No it shouldn't. It's a security risk.

why a security risk?

Because there's no authentication mechanism for it.

do you mean that any user can launch a command to modify touchpad settings, even if he doen's have an active X session?

Yes.

Ok, you're right.. it's a security risk. But is there another way to disable the touchpad? I filed this bug because I just wanted my hotkey working

Matthew, any suggestions on finding a better solution and providing some means of authenicating (eg. checking the Xauthority when updating).

This is broken/lacking for people and also means that the synclient tools can't be used to update the parameters for the touchpad.

Rewrite the synaptics driver to use an X extension for configuration.

Daniel: are there any other good drivers to use as an example and leech the code from for doing on-the-fly reconfiguration?

Not really, since you need a custom extension. Either that, or just tack stuff on to the ChangeDeviceControl part of XInput, and let Synaptics use a custom callback from ProcXChangeDeviceControl (or whatever it is) from Xi/chgdctl.c in xorg-server.

Since there's a script (/etc/acpi/asus-touchpad.sh) to disable the touchpad by using the dedicated shortkey on Asus laptops, why isn't the corresponding led working to tell te user the state of the touchpad (just like wled is going on where wireless is on) ?

I peak into /proc/acpi/asus and I didn't see anything like a touchpad led or so.
Can you please make something so that people who decide to use the touchpad shortkey (by turning SHMConfig "On") will see that led turning on when the shortkey is pressed ?

my asus laptop doesn't have any touchpad led!

M6 series don't have touchpad led ?
I have a V6, and here is the activity leds I have :
touchpad (goes on when tp is disabled), power on, charge, bluetooth, wifi.
I have just found some photos on the net, and you're right, M6 have CD led instead of touchpad one.

Whatever, isn't it a way to know if this led is detected in Ubuntu ? We can just leech a part of asus-wireless.sh to make the touchpad led goes on if we know how it is called among acpi devices...

You can check if the touchpad is active by doing:

synclient -l

There is an option TouchpadOff to tell you if its available.

Note: You must have this in your xorg.conf under the Inputdevice section of your touchpad:

Option "SHMConfig" "on"

Ram: the point of this bug is that it shouldn't use SHMConfig since this can not be activated by default.

duh.. sorry.. should have read the bug a bit thoroughly.

Same as bug #55235 and bug #27541.
And I hope this will be working securely some time soon!

Thanks for your report. Your idea might get more attention and have
the possibility of being implemented if you would submit a
specification for this.

You should first check whether it already exists at the Ubuntu specs
page (https://launchpad.net/distros/ubuntu/+specs) in Launchpad. If
that is the case, feel free to contact the drafter of that spec about
your comments/suggestions. Otherwise you can start writing a spec
following the steps described in
        https://wiki.ubuntu.com/FeatureSpecifications.

This issue is definitely a problem for me - as I'm on a MacBook (with only one mouse button), the default trackpad settings - quite frankly - leave a lot to be desired, and I can't configure it as-is without editing xorg.conf or opening a security hole (even then, gsynaptics is limited - for instance, there is no way to configure two-finger scroll or right-click tapping). I was able to adjust my acceleration (using the Mouse control panel) by setting my trackpad to be CorePointer, but not tapping/scrolling. I think this should be investigated again before Gutsy - as it stands, it is *impossible* to even change the trackpad acceleration without editing xorg.conf, which is unacceptable in a distribution targeted towards everyone. Either we could use SHMConfig and find a way to close the security hole, or we could use the Mouse control panel and CorePointer as suggested. I may give the source a look, but I'm rather C-impaired so I don't know what I'll make of it.

A basic implementation of this has been uploaded and should land in the repositories soon. The UI will be present in the mouse properties.This does not provide the full functionality of gsynaptics, but should cope with the common case of people wanting to alter the tapping and scrolling properties.