UserAgent: Mozilla/5.0 (X11; CrOS x86_64 11021.56.0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/70.0.3538.76 Safari/537.36
Platform: 11021.56.0 (Official Build) stable-channel eve

Steps to reproduce the problem:
Using Pixelbook
1. Connect an external mouse
2. Fold the device hinge >180 degrees

What is the expected behavior?
A normal, stable mouse pointer

What went wrong?
The mouse pointer flickers at what looks like about 15Hz

Did this work before? N/A 

Chrome version: 70.0.3538.76  Channel: n/a
OS Version: 11021.56.0
Flash Version: 

On my new external display (the problem still occurs with no ext display), when the pointer is in motion within about 1-2cm from the top-right corner, a second mouse pointer can be seen flickering in the very top-right of the display.  

Other users have reported this (or probably same) behaviour at e.g.
https://productforums.google.com/forum/#!msg/pixelbook/Lew63MojaIE/O62q1nyPAAAJ
https://productforums.google.com/forum/#!topic/chrome/-MV328Gd8Xk;context-place=topicsearchin/chrome/category$3Aolder-versions%7Csort:relevance%7Cspell:false
https://www.reddit.com/r/chromeos/comments/9c4583/chromebook_mouse_flicker/

I previously found better 3rd party examples when I reported this via feedback some months ago, but cannot find the same ones again.  I'm filing the bug now because I hadn't seen the top-right 'fake' mouse pointer before purchasing this new portable external monitor.  

It seems clear that there is a mouse position, or more accurately pointer-drawing-position issue, with a second, fixed, ghost-pointer being drawn at top-left (is that 0,0?) and alternately at the correct current-mouse-position.