in tp_init_softbuttons(), edit the width to e.g. 12mm, does that help? At what size does it become useful?

I'm happy to increase the size until it becomes usable for me and report back.

However part of the point is that while there might be a visual guide (but no tactile guide) most of the time while using the touchpad it's not actually visible (either due to my hands being over it or because it's a low-constrast guide which is almost invisible in low-light). So practically, for comfortable usage for me, i suspect it shouldn't be treated any different from a touchpad without the mark.

I was just about to start a new bug when I notice this one. I think I have same problem. This is same Dell 5510 that you solved on this other bug.  https://bugs.freedesktop.org/show_bug.cgi?id=97347.

There are 2 problems here. 1) no tactile middle button and 2) middle is now too small and too far to the left.

Here's my experience. Touchpad is no very wide, too big. Dell draws that line in the middle.  Like OP, I have trouble finding middle without a physical button.  I put a small braille sticker on edge of hand rest so thumb can find it. So I know where the middle is and can find it, even in the dark :)

But it is still difficult to find the middle button. 

Visualize bottom area, marker in middle

|-------------------------|-----------------------|

Libinput has the left, middle, and right button areas sectioned so that the middle only takes space away from the left, but not right. It feels like this

|-------left-------|middle|---------right---------|

Right is too big, left is too far left, and middle too small. Left is hard to reach. In order to hit the middle, it is necessary to be on left of center line. But exactly so.  Middle is very small, can only hit if thumb lands just left of the middle line.

I do not believe it was this way in libinput when we worked on it in relation to bug 97347.  I recall that clicking on the braille dot at the middle would cause a middle click.  Now definitely thumb must wander to left.

If I were allowed to choose, I would much rather have the division like this:

|-----------------left--|----middle-----|---right-|

I almost never need the right button and when I do need it, I don't need to look to find because boundary of touchpad.

In libinput's current setting, the left button is very far from my right thumb. The right thumb rests under the "n" key and I cannot reach the left button without lifting my hand from the keyboard entirely.

Oh, hell. While looking for instructions about how to use tp_init_softbuttons, I found out you made the middle too small on purpose:
https://lists.freedesktop.org/archives/wayland-devel/2016-July/030032.html

I wish you would let us decide for ourseleves.

(In reply to Paul Johnson from comment #3)
> Libinput has the left, middle, and right button areas sectioned so that the
> middle only takes space away from the left, but not right. It feels like this
> 
> |-------left-------|middle|---------right---------|

that's not true. look at
https://cgit.freedesktop.org/wayland/libinput/tree/src/evdev-mt-touchpad-buttons.c#n575
the left edge is 5mm left of the middle, the right edge 5mm right of the
middle.

Unless your axis ranges are out or there's some other bug interfering, the
middle button is centered.

> Oh, hell. While looking for instructions about how to use
> tp_init_softbuttons, I found out you made the middle too small on purpose:
> https://lists.freedesktop.org/archives/wayland-devel/2016-July/030032.html
> 
> I wish you would let us decide for ourseleves.

sigh. I absolutely hate loaded language like this. No, I didn't make it too small on purpose, I made it *smaller*, with an explanation and a link to the bug. Get your act together and assume that people have good intentions.

Thanks for the explanation. My axis must be out of whack, because the middle appears to the left of the center dividing line on the device. Am closing as invalid.

Run the touchpad-edge-detector tool (part of libevdev) and that should tell you the correct axis ranges. Then file a bug against systemd and cc me on it (@whot) so we can get this into the hwdb.

ping?

I did some informal testing, seems that at around 20mm it's much more convenient. Which is quite close the the 25% mark of my touchpad (101mm wide).

But again, by how i operate the laptop i can't normally actually see the marker. So it's not that surprising that a convenient size is going towards the same size as non-marked touchpads.

still waiting on the touchpad edge detector tool output from comment #6. Please re-open when the requested information is available.