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Click lock is a behavior where you do a button click once, the system
will register the click as "holding the button".
In laptop Thinkpad T450s I have an issue where the disabled touchpad
sometimes could trigger the click lock when clicking the trackpoint (red
pointing stick)'s left button.
Basically it happens randomly when my palm is touching the touchpad
while I'm clicking the trackpoint left button.
But I found a way to make the bug occurs easily:
1. Disable the touchpad first. You can do this from ubuntu's "Mouse & Touchpad"
setting.
2. Put your two fingers on the touchpad (whether your two fingers are
tapping or pressing the clickpad, it doesn't matter). You could use your
left hand's index and middle finger for this.
3. While your left hand's two fingers are on the touchpad, use your
right hand to click the trackpoint's left button once (don't hold it) on
the desktop area, then immediately move the cursor with the pointing
stick.
4. If the click lock effect gets triggered, you would see you make a
selection drag on the desktop area. If the click lock doesn't happen,
repeat again the step 3.
The evtest log on the trackpoint:
$evtest /dev/input/event15
Input driver version is 1.0.1
Input device ID: bus 0x11 vendor 0x2 product 0xa version 0x0
Input device name: "TPPS/2 IBM TrackPoint"
Supported events:
Event type 0 (EV_SYN)
Event type 1 (EV_KEY)
Event code 272 (BTN_LEFT)
Event code 273 (BTN_RIGHT)
Event code 274 (BTN_MIDDLE)
Event type 2 (EV_REL)
Event code 0 (REL_X)
Event code 1 (REL_Y)
Properties:
Property type 0 (INPUT_PROP_POINTER)
Property type 5 (INPUT_PROP_POINTING_STICK)
Testing ... (interrupt to exit)
Event: time 1496047216.720823, type 1 (EV_KEY), code 272 (BTN_LEFT), value 1
Event: time 1496047216.720823, -------------- SYN_REPORT ------------
Event: time 1496047216.778898, type 1 (EV_KEY), code 272 (BTN_LEFT), value 0
Event: time 1496047216.778898, -------------- SYN_REPORT ------------
Event: time 1496047220.234518, type 1 (EV_KEY), code 272 (BTN_LEFT), value 1
Event: time 1496047220.234518, -------------- SYN_REPORT ------------
If the click lock is not triggered, you would see BTN_LEFT's value 1 & 0:
Event: time 1496047216.720823, type 1 (EV_KEY), code 272 (BTN_LEFT), value 1
Event: time 1496047216.778898, type 1 (EV_KEY), code 272 (BTN_LEFT), value 0
But if the click lock is triggered, you would only see value 1:
Event: time 1496047220.234518, type 1 (EV_KEY), code 272 (BTN_LEFT),
value 1
I am guessing "value 0" means release the button. So when click lock is
happening, the button left is not released at all, thus it's producing
"hold the button" effect.
More Informations:
This issue doesn't happen on other OS like Windows, but I can confirm it
happens on most modern linux distro and DE I've tried (e.g. ubuntu v17/v16,
kubuntu, ubuntu mate, xubuntu, lubuntu, linux mint, fedora, open suse, etc). So
this issue must be coming from the synaptic touchpad driver, or maybe from the
kernel (?)
Also, the issue doesn't occur on older thinkpad models which doesn't use
same clickpad type touchpad, e.g. T430 or X230. For newer thinkpad
models (e.g. T460, X260, etc) which uses same clickpad design, same
issue might exists too (need confirmation though).
** Affects: linux (Ubuntu)
Importance: Low
Status: Incomplete
** Tags: touchpad trackpoint
--
[Thinkpad T450s] Click lock effect on trackpoint left button when touchpad is
disabled
https://bugs.launchpad.net/bugs/1694225
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