User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:22.0) Gecko/20100101 Firefox/22.0 (Beta/Release) Build ID: 20130618035212 Steps to reproduce: Tried to render two lines as polygons. They should not cross: <!--?xml version="1.0" encoding="UTF-8"?--> <!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.0//EN" "http://www.w3.org/TR/2001/REC-SVG-20010904/DTD/svg10.dtd"> <svg style="fill-opacity:1; stroke:black;" xmlns="http://www.w3.org/2000/svg" xlink="http://www.w3.org/1999/xlink" height="30" width="30"> <g transform="translate(10,10)" > <polygon style="fill:none; stroke-width:1;" points=" 0 5 0 -5"></polygon> <polygon style="fill:none; stroke-width:1;" points=" 0 5 -5 5"></polygon> </g> </svg> Actual results: The two lines cross (intersect). See attached screen-dump. Expected results: The two lines should meet at [0,5]

Seems to be connected with hardware acceleration. Turning it off stops the protrusion.

Regression range: good=2012-05-23 bad=2012-05-24 http://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=36e938e51481&tochange=f43e8d300f21 Suspected: Bas Schouten — Bug 715768: Enable Azure-Thebes wrapper by default for D2D. r=jrmuizel