Matt Mayfield authored Apr 04, 2020 and Peter Hutterer committed May 22, 2020

!292

 improved libinput's ability to detect multiple-finger clicks when
the fingers were not aligned close to horizontally. However that caused
thumb detection to fail in several use cases.

This patch restores thumb detection for
- 2+ finger physical clickpad presses
- resting thumb while two-finger scrolling
- touches in the thumb exclusion area during multi-finger taps
and improves pinch detection when thumb is centered below fingers.

It also further enhances the flexibility of finger position for 2-, 3-,
or 4-finger taps: if all tapping fingers land on the touchpad within a
short time (currently 100ms), they will all count regardless of
position (unless below the lower_thumb_line).

Signed-off-by: Matt Mayfield <mdmayfield@yahoo.com>