Button1Mask permanently set
Running Xubuntu 20.04.2 on Lenovo Thinkpad Yoga X1 gen 5. Xorg.0.log attached.
Original symptom: old xlib program (xv) goes into a tight loop. Cause of symptom: Button1Mask is always set in the event state. Confirmed by xev output (attached). Problem cleared by restarting server, but shouldn't be possible. Reproduction may be hard :)