It's not quite the hairline feature you're asking for, but I created a patch for a new display mode that makes "hairlines" (anything smaller than half a pixel on screen) more visible: https://gitlab.com/inkscape/inkscape/merge_requests/365
It's not quite the hairline feature you're asking for, but I created a patch for a new display mode that makes "hairlines" (anything smaller than half a pixel on screen) more visible: https:/ /gitlab. com/inkscape/ inkscape/ merge_requests/ 365