HP Envy x360: touch sequences don't reliably end
I have a HP Envy x360 13-ay0779ng and the touch screen has somewhat often problems with touch when using the pen (not 100% sure the pen is needed to cause the problems though). It's these two problems (that are probably related):
- libinput sends additional touch down events for a slot that already is down; because of how kwin_wayland counts touch events this causes problems. Is that a bug in libinput or should apps not rely on a touch sequence only having one LIBINPUT_EVENT_TOUCH_DOWN?
- sometimes a touch down event is triggered but no touch up or cancel event afterwards for that slot (like as if you'd be holding a finger down).
I have checked what exactly is happening by patching KWin to tell me on Wayland. I think that I have observed nr 2 on X as well but it might also be problem nr 1 that X doesn't handle correctly; the end result is the same.
In touchscreen.yml I recorded the first problem; I stopped it right after it happened, so it should be towards the end of the file, the slot was 0 if I remember that correctly.