When we mouseover on "export questions > Category" help button, an incorrect help title [[export category]] is displayed.
So we need to change the value of variable "$txt->exportcategory " as below.

Index: export.php
===================================================================
RCS file: /cvsroot/moodle/moodle/question/export.php,v
retrieving revision 1.28.2.6
diff -u -r1.28.2.6 export.php
— export.php 10 Oct 2007 21:09:34 -0000 1.28.2.6
+++ export.php 21 Dec 2007 20:49:53 -0000
@@ -29,7 +29,7 @@
$txt->exportname = get_string('exportname','quiz');
$txt->exportquestions = get_string('exportquestions', 'quiz');
$txt->fileformat = get_string('fileformat','quiz');

• $txt->exportcategory = get_string('exportcategory','quiz');
  + $txt->exportcategory = get_string('exportcategory','question');
  $txt->modulename = get_string('modulename','quiz');
  $txt->modulenameplural = get_string('modulenameplural','quiz');
  $txt->tofile = get_string('tofile','quiz');