Created attachment 129036 [details]
Recordings (the only tap registered was an accidental one)
Sometimes the touchpad registers unwanted taps.
Happens in Windows as well with Dell's touchpad drivers as shipped in Windows 10 (version 126.96.36.199) but not with Elantech's own drivers (version 188.8.131.52).
It does happen with the X11 Synaptics drivers as well, but it's fixable by setting higher values for FingerLow and FingerHigh (10 and 20 are the values that work best for me). With libinput, however, there's no way to adjust the sensitivity. With the X11 Synaptics drivers, these settings could be adjusted by the DE as well (see KDE's input settings controls).
As consequence, I for times have accidentally unselected text, selected text, clicked on buttons (sometimes leading to catastrophic consequences) and closed windows (sometimes multiple windows that were maximized), etc. For this reason, I'm classifying this bug as major. It can lead to user frustration and, sometimes, disasters.
Device: Dell Vostro 5470 laptop
OS: Fedora Workstation Linux 25 x86-64
libinput version: 1.5.901-1.fc25
Touchpad Width: 112mm
Touchpad Height: 77mm
Touchpad type: clickpad
$ udevadm info /sys/class/input/event5 > udevinfo
$ cat /sys/class/dmi/id/modalias
Created attachment 129037 [details]
Recordings 2 (the only tap registered was an accidental one)
Created attachment 129038 [details]
Recordings 3 (the only tap registered was an accidental one. This one also registered as a click-and-drag, prompting some text that was on the screen to be selected)
Created attachment 129039 [details]
Recordings 3 results on the screen
Actually, judging by the touch pressure values in the recordings, this should be fixed with the new pressure handling in libinput. Your touches have a general pressure in the range of 24 to 48 (reading this from a gnuplot, might be off by a little) and that falls squarely into the range now used by libinput (schmitt trigger for 30/25). I'm closing this as fixed, please re-open if this is still an issue, thanks.