There is no option in XFCE 4.12.1's Mouse and Touchpad settings on Debian 9.2.1 to enable tap-to-click with an ALPS touchpad. Found on a fresh full-XFCE-desktop installation on a Dell Latitude E5440 laptop; confirmed my experience not to be unique through just a bit of Googling: http://redd.it/6k9h5s If memory serves, this was displayed as an option previously (presumably when the xorg synaptics driver was the default); but that is being deprecated in favor of libinput. Currently, to enable tap-to-click on an ALPS touchpad on a recent Debian system requires editing an X11 config file as root. This should be possible (as it was previously) through the GUI, and without administrator access.
Ran into the same problem using both the 'synaptics' drivers and the 'libinput' drivers. Noticed that the "Touchpad" worked in other environments but not in XFCE. Seems that other Desktop Environments have their own "Mouse and Touchpad" as well but they have the option to select "Tapping" or the like. XFCE does not give you the Option in "Mouse and Touchpad" to add "Tapping". So went and looked in: /usr/share/X11/xorg.conf.d/ and my file name that contains the Touchpad settings were: Section "InputClass" Identifier "libinput touchpad catchall" MatchIsTouchpad "on" MatchDevicePath "/dev/input/event*" Driver "libinput" I got it to work by adding the line: "Option" "Tapping" "on" Here is what it looked like when added: Section "InputClass" Identifier "libinput touchpad catchall" MatchIsTouchpad "on" Option "Tapping" "on" MatchDevicePath "/dev/input/event*" Driver "libinput" My file was named: 40-libinput.conf After adding that option that file it worked perfectly and fixed the problem.
Forgot to mention I'm using: Debian 9.3 Stretch: XFCE 4.12.4-1
Re: Comment #1 There's a difference between "manually hardcoding in—as root—some system-wide config files that can only be reloaded by relogging" and "fixed the problem [which was that tap-to-click isn't GUI-enablable]". I, too, am using that workaround (it's a very functional workaround) however, the issue is to have this functionality exposed to non-root users on systems with libinput-powered touchpads, _through a GUI_ (so "un-breaking" it, because that WAS available in the GUI back when it was the xf86 synaptics driver) And just checking in that Debian 9.4 and Ubuntu 18 are still affected by it
Just realized this is a duplicate of #13809 Can someone merge these threads?
Marking as a duplicate as suggested. *** This bug has been marked as a duplicate of bug 13809 ***