Libinput ScrollButton "Toggle"

[Paul Ewing]

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? 

Thanks,
Paul Ewing