There is a problem with the javascript call in the toggle_display_by_id function contained in the file inc/misc/_misc.funcs:

when $text_when_displayed or $text_when_hidden contained a simple quote, there is an error. A solution is to put the following code:

/**
 * Generate a link that toggles display of an element on clicking.
 *
 * @todo Provide functionality to make those links accessible without JS (using GET parameter)
 * @uses toggle_display_by_id() (JS)
 * @param string ID (html) of the link
 * @param string ID (html) of the target to toggle displaying
 * @return string
 */
function get_link_showhide( $link_id, $target_id, $text_when_displayed, $text_when_hidden, $display_hidden = true )
{
	$html = "<a id=\"$link_id\" href=\"#\" onclick=\"return toggle_display_by_id('$link_id','$target_id','".jsspecialchars($text_when_displayed )."','".jsspecialchars( $text_when_hidden )."')\">"
		.( $display_hidden ? $text_when_hidden : $text_when_displayed )
		."</a>";

	return $html;
}


/**
 * Escapes strings to be included in javascript
 *
 * @param string s
 */
function jsspecialchars($s) {
   return preg_replace('/([^ !#$%@()*+,-.\x30-\x5b\x5d-\x7e])/e',
       "'\\x'.(ord('\\1')<16? '0': '').dechex(ord('\\1'))",$s);
}