if (this._monitor.childNodes.length) 
if (this._monitor.hasChildNodes()) 
  updatePosition: function (aPosition)  {    if (this._monitor.childNodes.length)      this._monitor.removeChild(this._monitor.firstChild);          this._position = aPosition;    if (this._position == kIShellService.BACKGROUND_TILE)      this._tileImage();    else if (this._position == kIShellService.BACKGROUND_STRETCH)      this._stretchImage();    else      this._centerImage();  },
5459	/local1/tlutelli/issta_data/temp/all_js/javascript/2007_temp/2007/5459/f932fa378f3c869b419186ccf62d7c6935c66364/setDesktopBackground.js/clean/browser/components/shell/content/setDesktopBackground.js