Re: Occasional random cursor movement while typing

["Elmer E. Dow" <elmeredow@att.net>]

Bob Proulx wrote:

Elmer E. Dow wrote:
  

When typing on my laptop, occasionally my cursor will skip back (up)
a few lines and I'll be entering text in the midst of text
...
What's happening here? My sleeve isn't touching the touchpad nor did
I bump the Trackpoint nor the mouse. I'm not accidentally hitting
    

I am confident it is the touchpad.  I have the same problem.
Disabling the touchpad will avoid the problem.  Personally I did not
want to unconditionally disable the touchpad.  I would use it more if
it were not for that annoying behavior.

The syndaemon gives me great relief and results.

  $ apt-cache show xserver-xorg-input-synaptics
    * It also provides a daemon to disable touchpad while typing at
      the keyboard and thus avoid unwanted mouse movements (see
      syndaemon(1)).

It detects keyboard activity and for a configurable time disables the
touchpad.  When idle is detected it enables the touchpad.

I launch it like this (in my ~/.xsession file, but you would need more
than this there).

  syndaemon -i 20 -K -p $HOME/var/run/syndaemon.pid -d

Bob
  

I discovered xserver-xorg-input-synaptics was already installed on my laptop, so I tried:

$ syndaemon -i 1.0

and got the message . . .

Can't access shared memory area. SHMConfig disabled?
$

A little research resulted in my finding instructions to add the following to the /etc/X11/xorg.conf file in order to enable SHMConfig:

Section "InputClass"
        Identifier "enable synaptics SHMConfig"
        MatchIsTouchpad "on"
        MatchDevicePath "/dev/input/event*"
        Driver "synaptics"
        Option "SHMConfig" "on"
EndSection

In typing the above, I discovered what's happening!!!!!

The cursor jumped again as I was typing the "t" in "little." I tried to replicate what I was doing and discovered that it's not the touchpad that I'm touching but the left clicker key situated in front of the touchpad. The return spring under that key has become weak and mushy over seven or eight years of almost daily service. As I reach to strike the "r" and "t" keys I sometimes brush the clicker key with the bottom of the lower thumb knuckle of the left hand. When that happens, the  cursor jumps to wherever the  mouse pointer happens to be and enters the character there.

I need to be careful to keep my left hand farther above the keys while typing. It would also be helpful to replace the spring under the left clicker key. (This diagnosis also explains why the problem has grown worse with age.)

Thanks to all for your patience and advice.


Elmer E. Dow