Reported by Nikolaus Schaller, Mar 29, 2018

unknown mouse event type=3, code=18, value=343
unknown mouse event type=3, code=18, value=0
unknown mouse event type=3, code=18, value=348
unknown mouse event type=3, code=18, value=3e3
unknown mouse event type=3, code=18, value=328
unknown mouse event type=3, code=18, value=329
unknown mouse event type=3, code=18, value=32e
unknown mouse event type=3, code=18, value=334
unknown mouse event type=3, code=18, value=0

This seem to be touch pressure events on QtMoko.

fgrep reveals these locations:

src/gui/embedded/qmouselinuxinput_qws.cpp:            
qWarning("unknown mouse event type=%x, code=%x, value=%x", 
data->type, data->code, data->value);
src/plugins/generic/linuxinput/qlinuxinput.cpp:            
qWarning("unknown mouse event type=%x, code=%x, value=%x", 
data->type, data->code, data->value);

It might suffice to disable QLINUXINPUT_EXTRA_DEBUG - or change the 
code.