<?xml version="1.0" encoding="UTF-8" ?>
<?xml-stylesheet href="chrome://global/skin/" type="text/css"?>
<!DOCTYPE window>
<window xmlns= "http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
<script>
function openFile() {
   var nsIFilePicker = Components.interfaces.nsIFilePicker;
   var fp = Components.classes["@mozilla.org/filepicker;1"].createInstance(nsIFilePicker);
   fp.init(window, "Select a File", nsIFilePicker.modeOpenMultiple);

   var res = fp.show();

   if (res == nsIFilePicker.returnOK){
     var fileEnum = fp.files;
      var item = null;
      var file = null; 

      while(fileEnum.hasMoreElements()) {
         item = fileEnum.getNext();

         file = item.QueryInterface(Components.interfaces.nsIFile);
         
         // Fill in information into listbox
         var cellName = document.createElement("listcell");
         cellName.setAttribute("label", file.leafName );
         
         var cellSize = document.createElement("listcell");
         cellSize.setAttribute("label", file.fileSize);
         
         var cellType = document.createElement("listcell");
         cellType.setAttribute("label", "test文件おの태으");

         var cellModified = document.createElement("listcell");
         cellModified.setAttribute("label", file.lastModifiedTime);
         
         var item = document.createElement("listitem");
         item.appendChild(cellName);
         item.appendChild(cellSize);
         item.appendChild(cellType);
         item.appendChild(cellModified);

         var list = document.getElementById("fileList");
         list.appendChild(item);
      }
   }
}
</script>

<hbox>
   <button label="Open..." oncommand="openFile()" />
</hbox>
<listbox id="fileList" seltype="multiple" flex="1">
  <listhead>
    <listheader label="Name"/>
    <listheader label="Size"/>
    <listheader label="Type"/>
    <listheader label="Modified" />
  </listhead>
  <listcols >
    <listcol flex="1"/>
    <listcol flex="1"/>
    <listcol flex="1"/>
      <listcol flex="1"/>   
  </listcols>
</listbox>   
</window>

Error: uncaught exception: [Exception... "Component returned failure code: 0x80520012 (NS_ERROR_FILE_NOT_FOUND) [nsIFile.fileSize]"  nsresult: "0x80520012 (NS_ERROR_FILE_NOT_FOUND)"  location: "JS frame :: chrome://findfile/content/test.xul :: openFile :: line 28"  data: no]

         var cellSize = document.createElement("listcell");
//         cellSize.setAttribute("label", file.fileSize);

         var cellModified = document.createElement("listcell");
//         cellModified.setAttribute("label", file.lastModifiedTime);