The bug is indeed in the 'Disable touchapad while typing' feature of the xserver-xorg-input-synaptics. I think the disable time(time to keep it disabled has to less). Or these special keys used frequently has to be omitted.

the time used by syndaemon can be specified on the commandline and modified for the distribution. please talk to your distribution maintainer if you want this shortened.

as for adding special key combos - no, sorry. this is quite complex to do, you'd need to find the keyboard combinations that make sense (and everyone has a different opinion on which ones should be excluded).

(In reply to comment #2)
> the time used by syndaemon can be specified on the commandline and modified for
> the distribution. please talk to your distribution maintainer if you want this
> shortened.
I have used syndaemon but the problem reported doesn't seem to actually linked to it. Here is it how..

While using syndaemon, I figure out that I had never used it before because I have not experienced such behaviour of my cursor before. This justifies that in System>Prefrences>Mouse [Touchpad]>Disable touchpad while typing option in Mouse Prefrences in Ubuntu (Gnome) does not link to syndaemon in background. It does disables by some other manner. 

I used syndaemon and while on desktop, when I press any key the cursor stucks there without any movement for 2s in a very regular manner, which is default in Ubuntu. However in the bug, I experienced that cursor stucks only when using some special keys like Ctrl+c, Ctrl+v etc. Moreover it doesn't happen every time but only sometimes when repeatedly trying to reproduce. I think I have mentioned correctly how to reproduce the bug in the bug description.

> 
> as for adding special key combos - no, sorry. this is quite complex to do,
> you'd need to find the keyboard combinations that make sense (and everyone has
> a different opinion on which ones should be excluded).
I understand that

I doubt that

(In reply to comment #3)
> While using syndaemon, I figure out that I had never used it before because I
> have not experienced such behaviour of my cursor before. This justifies that in
> System>Prefrences>Mouse [Touchpad]>Disable touchpad while typing option in
> Mouse Prefrences in Ubuntu (Gnome) does not link to syndaemon in background. It
> does disables by some other manner. 

did you check the source? upstream gnome uses syndaemon in the background, so unless Ubuntu patches it out and uses something else, syndaemon is running.
easiest check is "ps aux | grep syndaemon" to see if it is running in the background.

syndaemon has two modes, one with xrecord, one polling one. if U compiles with xrecord enabled (don't know if they do), that may also be part of the issue. I'm not sure how well the xrecord mode works, I don't use it myself.

But Peter strange thing is that all symptoms of the problem disappears, when
I remove the xserver-xorg-input-synaptics package as I have stated in the
Ubuntu bug report. Still I have the curiosity to know, whether you can
reproduce the issue in your system or not?

On Mon, Nov 8, 2010 at 11:10 AM, <bugzilla-daemon@freedesktop.org> wrote:

> https://bugs.freedesktop.org/show_bug.cgi?id=31259
>
> --- Comment #5 from Peter Hutterer <peter.hutterer@who-t.net> 2010-11-07
> 21:40:15 PST ---
> (In reply to comment #3)
> > While using syndaemon, I figure out that I had never used it before
> because I
> > have not experienced such behaviour of my cursor before. This justifies
> that in
> > System>Prefrences>Mouse [Touchpad]>Disable touchpad while typing option
> in
> > Mouse Prefrences in Ubuntu (Gnome) does not link to syndaemon in
> background. It
> > does disables by some other manner.
>
> did you check the source? upstream gnome uses syndaemon in the background,
> so
> unless Ubuntu patches it out and uses something else, syndaemon is running.
> easiest check is "ps aux | grep syndaemon" to see if it is running in the
> background.
>
> syndaemon has two modes, one with xrecord, one polling one. if U compiles
> with
> xrecord enabled (don't know if they do), that may also be part of the
> issue.
> I'm not sure how well the xrecord mode works, I don't use it myself.
>
> --
> Configure bugmail: https://bugs.freedesktop.org/userprefs.cgi?tab=email
> ------- You are receiving this mail because: -------
> You reported the bug.
>

(In reply to comment #6)
> But Peter strange thing is that all symptoms of the problem disappears, when
> I remove the xserver-xorg-input-synaptics package as I have stated in the
> Ubuntu bug report. Still I have the curiosity to know, whether you can
> reproduce the issue in your system or not?

syndaemon is part of the synaptics package, so in removing the package, you're also removing syndaemon.

and yes, I can reproduce it and it's caused by syndaemon on my machine. ps shows it running, the timeout for the cursor to continue moving is 0.5 seconds (which is the argument syndaemon is started with). you say you see 2 seconds, which is the default for syndaemon.

Peter unfortunately my laptop has got some problem, so its gone for repair.
So when I have the laptop, I will let you know the better details related to
the bug.

For now, the delay I told you are caused only for particular key
combinations like Ctrl+C, Ctrl+V etc and not normally. So the delay is more
for this key combinations. When I move the cursor randomly and I press these
keys, the cursor gets stuck for some time and there is no motion despite I
continuously move finger on the touchpad. Moreover the cursor stuck only
sometimes not always when you repeatedly press these keys combinations. For
rest all keys there is no interruption in the movement of the cursor when
the key is pressed. This happens for all users of Gnome (KDE i'm not sure)..


On Tue, Nov 9, 2010 at 3:42 AM, <bugzilla-daemon@freedesktop.org> wrote:

> https://bugs.freedesktop.org/show_bug.cgi?id=31259
>
> --- Comment #7 from Peter Hutterer <peter.hutterer@who-t.net> 2010-11-08
> 14:12:12 PST ---
> (In reply to comment #6)
> > But Peter strange thing is that all symptoms of the problem disappears,
> when
> > I remove the xserver-xorg-input-synaptics package as I have stated in the
> > Ubuntu bug report. Still I have the curiosity to know, whether you can
> > reproduce the issue in your system or not?
>
> syndaemon is part of the synaptics package, so in removing the package,
> you're
> also removing syndaemon.
>
> and yes, I can reproduce it and it's caused by syndaemon on my machine. ps
> shows it running, the timeout for the cursor to continue moving is 0.5
> seconds
> (which is the argument syndaemon is started with). you say you see 2
> seconds,
> which is the default for syndaemon.
>
> --
> Configure bugmail: https://bugs.freedesktop.org/userprefs.cgi?tab=email
> ------- You are receiving this mail because: -------
> You reported the bug.
>

https://bugzilla.gnome.org/show_bug.cgi?id=639487