Index: functions/i18n.php
===================================================================
--- functions/i18n.php	(revision 14363)
+++ functions/i18n.php	(working copy)
@@ -159,15 +159,17 @@
 }
 
 /**
- * Converts string from given charset to charset, that can be displayed by user translation.
+ * Converts a string from the given $charset to a character set that
+ * can be displayed by the current user interface language (translation)
  *
- * Function by default returns html encoded strings, if translation uses different encoding.
+ * Function by default returns html encoded strings if translation uses
+ * different encoding.
  * If Japanese translation is used - function returns string converted to euc-jp
  * If $charset is not supported - function returns unconverted string.
  *
  * sanitizing of html tags is also done by this function.
  *
- * @param string $charset
+ * @param string $charset The charset of the incoming string
  * @param string $string Text to be decoded
  * @param boolean $force_decode converts string to html without $charset!=$default_charset check.
  * Argument is available since 1.4.5 and 1.5.1.
@@ -184,7 +186,7 @@
     }
 
     /* All HTML special characters are 7 bit and can be replaced first */
-    if (! $save_html) $string = sm_encode_html_special_chars ($string);
+    if (! $save_html) $string = sm_encode_html_special_chars($string, ENT_COMPAT, $charset);
     $charset = strtolower($charset);
 
     set_my_charset();
Index: functions/strings.php
===================================================================
--- functions/strings.php	(revision 14382)
+++ functions/strings.php	(working copy)
@@ -1489,7 +1489,13 @@
   *                   (See http://php.net/manual/function.htmlspecialchars.php )
   *                   (OPTIONAL; default ENT_COMPAT)
   * @param string $encoding The character encoding to use in the conversion
-  *                         (OPTIONAL; default automatic detection)
+  *                         (if not one of the character sets supported
+  *                         by PHP's htmlspecialchars(), then $encoding
+  *                         will be ignored and iso-8859-1 will be used,
+  *                         unless a default has been specified in
+  *                         $default_htmlspecialchars_encoding in
+  *                         config_local.php) (OPTIONAL; default automatic
+  *                         detection)
   * @param boolean $double_encode Whether or not to convert entities that are
   *                               already in the string (only supported in
   *                               PHP 5.2.3+) (OPTIONAL; default TRUE)
@@ -1500,6 +1506,31 @@
 function sm_encode_html_special_chars($string, $flags=ENT_COMPAT,
                                       $encoding=NULL, $double_encode=TRUE)
 {
+
+   // charsets supported by PHP's htmlspecialchars
+   // (move this elsewhere if needed)
+   //
+   static $htmlspecialchars_charsets = array(
+      'iso-8859-1', 'iso8859-1',
+      'iso-8859-5', 'iso8859-5',
+      'iso-8859-15', 'iso8859-15',
+      'utf-8',
+      'cp866', 'ibm866', '866',
+      'cp1251', 'windows-1251', 'win-1251', '1251',
+      'cp1252', 'windows-1252', '1252',
+      'koi8-R', 'koi8-ru', 'koi8r',
+      'big5', '950',
+      'gb2312', '936',
+      'big5-hkscs',
+      'shift_jis', 'sjis', 'sjis-win', 'cp932', '932',
+      'euc-jp', 'eucjp', 'eucjp-win',
+      'macroman',
+   );
+
+
+   // if not given, set encoding to the charset being
+   // used by the current user interface language
+   //
    if (!$encoding)
    {
       global $default_charset;
@@ -1508,6 +1539,21 @@
       $encoding = $default_charset;
    }
 
+
+   // make sure htmlspecialchars() supports the needed encoding
+   //
+   if (!in_array(strtolower($encoding), $htmlspecialchars_charsets))
+   {
+      // use default from configuration if provided or hard-coded fallback
+      //
+      global $default_htmlspecialchars_encoding;
+      if (!empty($default_htmlspecialchars_encoding))
+         $encoding = $default_htmlspecialchars_encoding;
+      else
+         $encoding = 'iso-8859-1';
+   }
+
+
    if (check_php_version(5, 2, 3))
       return htmlspecialchars($string, $flags, $encoding, $double_encode);