Pinch gesture on Ubuntu 18.04

Hi guys,
I’m trying to use touchscreen on ubuntu 18.04. And my enviroment is as belows:

ubuntu 18.04
QT 5.12.9
vtk 9.1

I build the TouchGestureViewer example. Everything works fine, including single-touch, rotate, except the pinch gesture. No responding when I try to zoom the window using pinch.

I guess the window just do not recognize the multitouch gesture. But the pinch gesture do great for Chrome on Ubuntu 18.04, very fluent expeirence.

I tried the same example on Windows 10, and it works fine. Same situation for 3D slicer.

I know the multitouch is tested for Windows and Mac. But any one could give me any direction I should go deeper? Thanks very much.