Clickfinger: drop-thumb-then-index-finger-then-move-index-finger interpreted as a two-finger scroll gesture
Summary
In clickfinger mode with a buttonless touchpad, dropping a thumb and then an index finger and then moving just the index finger is erroneously interpreted as a two-finger scroll
Steps to reproduce
- Use the RMI4 driver
- Use Clickfinger mode
- Find some content that is both vertically and horizontally scrollable and put the cursor on top of it
- Drop your thumb onto the bottom of the touchpad
- Less than quarter of a second later, drop your index finger onto the top part of the touchpad and start moving just that finger (the thumb remains stationary)
With my hardware, this activity is reliably interpreted by libinput as a two-finger scroll gesture, despite the fact that only one finger is moving, and one of them is obviously a thumb rather than a finger.
Two-finger scrolling should never be invoked when one of the fingers is a thumb, or when one of the two fingers on the pad is much higher or lower on the pad than the other finger
libinput version you encountered the bug on
1.13.0
Hardware information:
Late 2016 HP Spectre x360 with buttonless touchpad