Don't use singleton Variables object.

This may already have been altered, so get a pristine instance of the request
variables.
This was a real-world problem when clicking on "Show All Parts".

framework/Core/lib/Horde.php

@@ -728,7 +728,7 @@ public static function selfUrlParams(array $opts = array())
     {
         $vars = isset($opts['vars'])
             ? $opts['vars']
-            : $GLOBALS['injector']->getInstance('Horde_Variables');
+            : $GLOBALS['injector']->createInstance('Horde_Variables');
 
         $url = self::selfUrl(
             false,