Fix: Tab module=0 was disabled

htdocs/admin/modules.php

@@ -32,7 +32,7 @@ require_once(DOL_DOCUMENT_ROOT."/lib/admin.lib.php");
 $langs->load("errors");
 $langs->load("admin");
 
-$mode=GETPOST("mode")?GETPOST("mode"):(isset($_SESSION['mode'])?$_SESSION['mode']:0);
+$mode=isset($_GET["mode"])?GETPOST("mode"):(isset($_SESSION['mode'])?$_SESSION['mode']:0);
 $mesg=GETPOST("mesg");
 
 if (!$user->admin)