NBT + Pro Sites integration

nbt-pro-sites.php

<?php
add_filter( 'psts_setting_checkout_url', 'katarzyna_nbt_pro_sites_checkout_url' );
function katarzyna_nbt_pro_sites_checkout_url( $value ) {
	global $pagenow, $psts;

	if ( ! is_object( $psts ) )
		return $value;

	$show_signup = $psts->get_setting( 'show_signup' );

	if ( ! is_admin() && 'wp-signup.php' == $pagenow && $show_signup && isset( $_REQUEST['blog_template'] ) ) {
		$value = add_query_arg( 'blog_template', $_REQUEST['blog_template'], $value );
	}

	return $value;
}