To make the mode "Dynamic" at the login screen you need to edit the ./imp/login.php file. Search for the code that looks like this:
/* If DIMP/MIMP are available, show selection of alternate views. */
$views = array();
if (!empty($conf['user']['select_view'])) {
$apps = $registry->listApps(null, true);
if (isset($apps['dimp']) || isset($apps['mimp'])) {
$views[] = array('sel' => false, 'val' => 'imp', 'name' => _("Traditional"));
if (isset($apps['dimp'])) {
$views[] = array('sel' => true, 'val' => 'dimp', 'name' => _("Dynamic"));
}
if (isset($apps['mimp'])) {
$views[] = array('sel' => false, 'val' => 'mimp', 'name' => _("Minimalist"));
}
}
}