adds two links at the bottom of the popup Help window;
1. a link to the same help page but in English.
2. a link back, to an help page in my current chosen language.

usually useful when there is bad translation or that the translation is missing.

open "help.php" . just after the line:

echo '<p class="helpindex"><a href="help.php?file=index.html">'. get_string('helpindex') .'</a></p>';

add these lines:

// see this help page in english (most of the time, more readble and easy to understand then the translation)
echo '<p class="helpindex"><a href="help.php?file='.$file.'&module='.$module.'&forcelang=en_utf8">English Version of this Help page</a></p>';
// go back to my local preferred language
echo '<p class="helpindex"><a href="help.php?file='.$file.'&module='.$module.'&forcelang='.current_language().'">'.get_string('helpinyourlanguage').'</a></p>';
// make sure english help files are ALWAYS displayed visually correct
if ($forcelang == 'en_utf8') echo '<style>body,p,h1,h2,h3

</style>';