rem: var text = document.createElementNS(kXUL_NS, "label"); text.setAttribute("id", "noPreviewAvailable"); text.setAttribute("value", bundle.getString("DesktopBackgroundNoPreview")); this._monitor.appendChild(text); 
add: this._monitor.appendChild(canvas); 
context:   _tileImage: function ()  {    var bundle = document.getElementById("backgroundBundle");    this._monitor.style.backgroundColor = "white";    var text = document.createElementNS(kXUL_NS, "label");    text.setAttribute("id", "noPreviewAvailable");    text.setAttribute("value", bundle.getString("DesktopBackgroundNoPreview"));    this._monitor.appendChild(text);  },
meta: 10520	/local1/tlutelli/issta_data/temp/all_js/javascript/2007_temp/2007/10520/86916c41e0932684d6a2c23fce12ce138ff4b782/setDesktopBackground.js/buggy/browser/components/shell/content/setDesktopBackground.js