Comment # 12 on bug 1206804 from Stefan Dirsch

Well, what you need is to map the input device to the RandR crtc.

Here is an example.

### figure out the input id of the touchscreen
# xinput list
[...]
���������   ��������� wch.cn USB2IIC_CTP_CONTROL                id=15   [slave  pointer  (2)]
[...]

(dis- and reconnecting helps to figure out how it is called; just as  a hint)

### figure out the RANDR ctrc
# xrandr
[...]
DVI-I-1-1 connected 1024x600+3840+0 (normal left inverted right x axis y axis)
476mm x 268mm

### Now do the mapping
# xinput --map-to-output 15 DVI-I-1-1

Does this help?