return elem.ownerDocument .defaultView .getComputedStyle(aElem, "").getPropertyValue(prop); 
return aElem.ownerDocument .defaultView .getComputedStyle(aElem, "").getPropertyValue(aProp); 
  getComputedStyle: function(aElem, aProp) {    return elem.ownerDocument               .defaultView               .getComputedStyle(aElem, "").getPropertyValue(prop);  },
5459	/local1/tlutelli/issta_data/temp/all_js/javascript/2007_temp/2007/5459/c9e2ada8f5ad3b906e4036c77d4401bdbcf94edc/nsContextMenu.js/buggy/browser/base/content/nsContextMenu.js