theme switching
At login time, we want to show our own theme (not the default one).
So please change: /usr/local/ispconfig/interface/lib/app.inc.php line 80
if(empty($_SESSION['s']['theme'])) $_SESSION['s']['theme'] = $conf['theme'];
to
$_SESSION['s']['theme'] = $conf['theme'];
Then the configured theme works at login time as aspected.