Libinput ScrollButton "Toggle"

[Peter Hutterer]

On Sat, Mar 16, 2019 at 09:17:20PM -0400, Paul Ewing wrote:
> Hello,
> 
> I have a question regarding the "ScrollButton" option in libinput. I recently
> purchased a trackball and I'd like to be able to configure it such that I can
> press the button that I've set as the ScrollButton and then use the ball for
> scrolling purposes. However, due to dexterity problems in my hand, I would
> prefer not to hold the button down.
> 
> I've tried to use the DragLockButtons option to take care of logically locking
> the button I've assigned as the ScrollButton but it doesn't seem to work. This
> is what my configuration currently looks like:
> 
> # /usr/share/X11/99-trackball.conf
> Section "InputClass"
>     Identifier      "Elecom DEFT Pro Trackball"
>     MatchProduct    "DEFT Pro TrackBall"
>     Driver          "libinput"
>     Option          "DragLockButtons" "10 10"
>     Option          "ScrollButton" "10"
>     Option          "ScrollMethod" "button"
> EndSection
> 
> If I hold button 10, I can scroll; however, it doesn't lock when I press it.
> Can anyone confirm if the functionality I'm trying to get is possible or if my
> configuration has any glaring issues? 

it's not implemented yet, please file an RFE for libinput for this.

The technical reason in this case: button scrolling is a libinput feature,
draglock is a feature implemented in the xorg driver. so by the time the
drag lock for button 10 activates, libinput is already done with that
button.

Cheers,
   Peter