On macOS and Windows, when you move the cursor around at high enough speed, an accidental second finger touch on the trackpad does not stop the cursor. Instead, the second finger is ignored, and cursor movement continues. This is very comfortable, as it allows one to rest fingers on the trackpad while doing large mouse movements, e.g. crossing the screen. Linux, however, immediately switches to two-finger touch (i.e. scroll) as soon as you touch the trackpad, irrespective of current cursor speed. This results in frequent, inconvenient, accidental missed targets or random scrolls where the intent was really mouse movement. This is especially annoying for people who switch back and forth between Linux and other platforms. If the cursor is presently moving at high enough speed, it is unlikely that the person wants to immediately convert that movement to fast scrolling in the same direction. It seems much more likely that the second finger is simply touching the trackpad because it's a natural resting position. Suggestion: Define a speed threshold above which an incoming second touch is ignored. This could be an option if some people really prefer the current behaviour.
Can you test macos and/or windows to figure out the parameters they're using? Would be useful to have a writeup of what you think happens there, mainly for comparision/inspriration.
(In reply to Peter Hutterer from comment #1) > Can you test macos and/or windows to figure out the parameters they're > using? Would be useful to have a writeup of what you think happens there, > mainly for comparision/inspriration. On macOS, if I move the mouse cursor with one finger, and then drop a second finger while the cursor is on a window that can scroll, I observe the following (test done by moving the cursor from top to bottom): # If my mouse cursor is travelling at about 100px/s or more, the second finger has no visible effect. The cursor keeps moving. # If my mouse cursor is moving at 20px/s or less, then the second finger immediately activates scrolling much like in Linux. It's hard to measure the threshold precisely. I don't know of a tool for that. I'll do a test under Windows if I can revive my last PC laptop.
(In reply to Peter Hutterer from comment #1) > Can you test macos and/or windows to figure out the parameters they're > using? Would be useful to have a writeup of what you think happens there, > mainly for comparision/inspriration. I may have been somewhat optimistic about Windows doing the right thing ;-) I just tested on a HP Envy dv6, and apparently, the behavior is similar to Linux. I probably did not pay much attention because the trackpad on this machine is so small you tend to naturally have the second finger outside of the tracking area anyways. It was actually quite hard to reach any kind of speed with such a tiny tracking area.
Any chance you want to work on this feature? :)
(In reply to Peter Hutterer from comment #4) > Any chance you want to work on this feature? :) I can try to take a look, but I'm not familiar at all with the code that deals with that.
Ok, I have a preliminary patch for this feature available now for testing: https://github.com/whot/libinput/tree/wip/ignore-moved-touches Let me know how you go, it still needs a bit of tuning but I think that's roughly the behaviour we want?
branch has been updated, and the patchset is on the list https://lists.freedesktop.org/archives/wayland-devel/2017-September/034897.html
commit de5246dae0201ea951715f62da806f90321978c5 Author: Peter Hutterer <peter.hutterer@who-t.net> Date: Wed Jun 21 12:29:52 2017 +1000 touchpad: use motion speed to ignore accidental 2fg touches
This change fixes the issue for me!
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