evdev picks up eGalax 0eef:a001 touchscreen, which is exposed through USB->HID Generic->Event Interface, as a touchpad, which results in the touchscreen being unusuable.
For futher information refer to  and . A simple hack has been proposed on Ubuntu Forums , which solves the issue in that touchpad capabilities are completely taken out of evdev.
Created attachment 52847 [details]
Xorg.0.log of faulty behaviour
Note, that not only does EVDEV misinterpret the device as Touchpad, but XOrg also matches it as a Touchpad rather than as a Touchscreen when applying the configuration.
[ 5562.153] (II) config/udev: Adding input device eGalax_eMPIA Technology Inc. PCAP MultiTouch Controller (/dev/input/event8)
[ 5562.153] (**) eGalax_eMPIA Technology Inc. PCAP MultiTouch Controller: Applying InputClass "evdev touchpad catchall"
[ 5562.153] (II) Using input driver 'evdev' for 'eGalax_eMPIA Technology Inc. PCAP MultiTouch Controller'
[ 5562.153] (II) Loading /usr/lib/xorg/modules/input/evdev_drv.so
As discussed in the thread on linuxwacom-devel, it turned out that the problem lies in the capabilities which the kernel reports, among which Buttons are defined, mich makes evdev think the pad was a mouse.