On a fresh installed Ubuntu 16.04 on a Lenovo P40 Yoga, the virtual keyboard does not take into account the touch events, but the mouse clicks are correctly recognized.

Reproducibility: This issue affects the virtual keyboard example and other projects.
The issue is not affecting windows, nor the built in virtual keyboard (onboard)

You can find attached to this report the output of a xev command, if it can help, the only lead i can think of being the MotionNotify event between the ButtonPress and ButtonRelease events, but if I try to « replicate » this behavior by moving the mouse between press and release, the keyboard behave as expected.