[aspiers]

Hrm, I just checked and actually I suspect it's the same with fingers.  Sorry if I initially led you down the wrong path.  So maybe the issue is specific to ChromeOS devices, or even the Pixel Slate in particular.  Wild guess - could it perhaps be related to the fact that the device is very high resolution?  It's 3000x2000, so presumably that means a lot more pixels to track per annotation line than most devices?