Tapping still works in the palm detection zones, some palms are detected as tap events. In my case it's actually the top software button areas that I trigger the most, the top right of the touchpad so I tend to randomly click wherever the pointer is when typing. I think it's fair to disable tapping in the edge regions, even if the regions overlap with software buttons (at least the top ones, don't think we need to worry abou the bottom ones).
http://lists.freedesktop.org/archives/wayland-devel/2015-April/021335.html
commit 39f11253471500cd380c8977b8cbe0683abe6b1d Author: Peter Hutterer <peter.hutterer@who-t.net> Date: Wed Apr 15 15:21:08 2015 +1000 touchpad: don't allow taps in the top half of the palm exclusion zone.
Use of freedesktop.org services, including Bugzilla, is subject to our Code of Conduct. How we collect and use information is described in our Privacy Policy.