XServer touchscreen one finger instead of two finger scrolling

Question

Problem:

My touchscreen device does not scroll on touching it with one finger, which is desired, but only when touching it with two fingers.

Technology stack:

• Linux kernel 4.9.81-intel-pk-standard
• custom distro via yocto
• Xserver (X.Org X Server 1.19.3)
• QtWebEngine (Qt5.9)
• Chromium

Further info:

• I guess it is an Xserver Problem, since it's got to be Xserver or the web stuff, but I can rule out the web stuff because I can access the UI remotely from a desktop PC's chrome browser, use chrome's inspect function to simulate a touch device and scroll the UI with the simulated (single finger) touch.
• The two fingers need to be at least about 2cm apart so that scrolling works (this might be irrelevant)

Answer 1

Apparently I was wrong and it was not an Xserver problem, but a Qt / qml problem: The QQuickWidget representation of the window needed to accept Touch events.