JOGL Version 2.3.1 (March 27, 2015)
When NewtCanvas is on my secondary monitor:
First call GLWindow.warpPointer(0, 0);
The next mouseMoved event from com.jogamp.newt.event.MouseListener gives position of 1, 0
When NewtCanvas is on my primary monitor, it works as expected and gives position of 0, 0
It is perhaps worth noting that I have a mixed resolution dual display, where my primary monitor is 1920x1200 and my secondary monitor is 1920x1080.
Also worth noting that I did not experience this issue in a much older former version (build 2.1.2 Nov 01, 2013)
Note - after further debugging, it appears that this happens when the canvas center's X coordinate is < 0.