OK, here it is, figured it out:
function load_script($fieldname)
{
return
//************************* START MODIFICATION
'var help = function () {alert(' . '"EDITOR HELP:\n\n' .
'Your help text here.\n\n' .
'It can be multiple lines.\n\n' .
');}' . "\n" .
'var options = { handler: help, title: "Editor help" };' . "\n" .
//************************* END MODIFICATION
'var converter = Markdown.getSanitizingConverter();' . "\n" .
'var editor = new Markdown.Editor(converter, "-'.$fieldname.'", options);' . "\n" .
'editor.run();' . "\n";
}
You might also want to modify the CSS for the markdown plugin in order to make sure that the editor and preview windows expand to fill the content area:
.wmd-input {
/* 604 */
width: 100%; /* <<<<< THIS CHANGED */
height: 250px;
margin: 0 0 10px;
padding: 2px;
border: 1px solid #ccc;
}
.wmd-preview {
/* 604 */
width: 100%; /* <<<<< THIS CHANGED */
margin: 10px 0;
padding: 8px;
border: 2px dashed #ccc;
}