So if I am using the file browser for instance, and trying to select a particular 2 or three files it will at random, either drop focus on those files or go and perform the default action for selecting those files. I cannot work out yet what is causing this erratic behaviour, and I also cannot say "it always does this wrong", as to me at least the behaviour is not deterministic.

Trackpad desired behaviour is right click to select options etc for the context, left click to select the folder/file/text/url etc,

In what way does your current configuration differ from this? How is it lacking? I can see that tap-to-click is disabled, is that what you want?

What does "erratic" mean, exactly? It is almost impossible to help you if I can't understand what the problem is.

I would actually recommend switching from the crusty old synaptics & evdev drivers to the newer libinput version:

# apt install xserver-xorg-input-{libinput,synaptics-,evdev-}

If you're a fan of multi-touch gestures then xserver-xorg-input-mtrack is another possibility.

No.

synclient
Parameter settings:
    LeftEdge                = 1751
    RightEdge               = 5191
    TopEdge                 = 1624
    BottomEdge              = 4282
    FingerLow               = 25
    FingerHigh              = 30
    MaxTapTime              = 180
    MaxTapMove              = 222
    MaxDoubleTapTime        = 180
    SingleTapTimeout        = 180
    ClickTime               = 100
    EmulateMidButtonTime    = 75
    EmulateTwoFingerMinZ    = 282
    EmulateTwoFingerMinW    = 7
    VertScrollDelta         = 101
    HorizScrollDelta        = 101
    VertEdgeScroll          = 0
    HorizEdgeScroll         = 0
    CornerCoasting          = 0
    VertTwoFingerScroll     = 1
    HorizTwoFingerScroll    = 0
    MinSpeed                = 1
    MaxSpeed                = 1.75
    AccelFactor             = 0.0395883
    TouchpadOff             = 0
    LockedDrags             = 0
    LockedDragTimeout       = 5000
    RTCornerButton          = 0
    RBCornerButton          = 0
    LTCornerButton          = 0
    LBCornerButton          = 0
    TapButton1              = 0
    TapButton2              = 0
    TapButton3              = 0
    ClickFinger1            = 1
    ClickFinger2            = 1
    ClickFinger3            = 1
    CircularScrolling       = 0
    CircScrollDelta         = 0.1
    CircScrollTrigger       = 0
    CircularPad             = 0
    PalmDetect              = 0
    PalmMinWidth            = 10
    PalmMinZ                = 200
    CoastingSpeed           = 20
    CoastingFriction        = 50
    PressureMotionMinZ      = 30
    PressureMotionMaxZ      = 160
    PressureMotionMinFactor = 1
    PressureMotionMaxFactor = 1
    GrabEventDevice         = 0
    TapAndDragGesture       = 1
    AreaLeftEdge            = 0
    AreaRightEdge           = 0
    AreaTopEdge             = 0
    AreaBottomEdge          = 0
    HorizHysteresis         = 25
    VertHysteresis          = 25
    ClickPad                = 0

Do I actually need the xinput package to get this functionality to work, or is it just useful for debugging?

I really cannot work out yet what needs to be changed.

Well explain exactly how you want the touchpad to behave (in as much detail as possible please) and post the full output of

synclient

Please use code tags when posting terminal output. Use the "quote" button on this post to see how I have made the above code block. No need to include the quote in your reply though. Thanks.

Also when I am scrolling with the mouse, not touching the buttons, and no where near the trackpad, sometimes the mouse behaves as if it has "follow focus" behaviour, and at other times it definitely needs the click.
Then a single click while over a folder sometimes causes that folder to be highlighted, and at other times it automatically behaves as if it got a double click and takes the focus into the folder.
I really cannot work out yet what needs to be changed.

when I type xinput it tells me the command is not found

The xinput command is supplied by the xinput package

See also https://wiki.debian.org/WhereIsIt#A.22I … tall.3F.22

What parts need to be corrected? In what way is the current configuration unsatisfactory?

Have you tried disabling the TapButtons? See the last post in the linked thread but set each of those options to zero (0).

If you still want taps to be recognised as clicks then perhaps try changing the MaxTapTime option.

I tried to follow this link:
https://dev1galaxy.org/viewtopic.php?id=2930
BUT when I type xinput it tells me the command is not found, so I am missing something that needs to be installed.

synclient gives me a sensible list of many values, but I need to get the other parts corrected

It is a Lenovo W520 that has given good service.
The mouse and trackpad behaviour under Devuan are so flaky as to make it almost impossible to use the GUI! sometimes triggering as if pressed when you merely scroll.

inxi
CPU: Quad Core Intel Core i7-2670QM (-MT MCP-) speed/min/max: 797/800/3100 MHz Kernel: 5.10.0-9-amd64 x86_64 Up: 7h 03m
Mem: 2627.7/23825.2 MiB (11.0%) Storage: 2.73 TiB (49.5% used) Procs: 254 Shell: Bash inxi: 3.3.01