http://www.cnblogs.com/ksmile/p/4567009.html
关键代码：
文件editor-app/editor/toolbar-default-actions.js
// Parse dom to string
var svgDOM = DataManager.serialize(svgClone);
//copy from internet #s2016-04-01
svgDOM = svgDOM.replace(/marker-start="url\("#/g,"marker-start=\"url(#").replace(/start"\)"/g,"start\)\"");
svgDOM = svgDOM.replace(/marker-mid="url\("#/g,"marker-mid=\"url(#").replace(/mid"\)"/g,"mid\)\"");
svgDOM = svgDOM.replace(/marker-end="url\("#/g,"marker-end=\"url(#").replace(/end"\)"/g,"end\)\"");
//copy from internet #e