example-blueprint.php

<?php if(!defined('KIRBY')) exit ?>

title: Event
pages: false
files: true
fields:
  title:
    label: Title
    type:  text
  course:
    label: Event location
    type:  pageselect
    path:  mypage/locations
  text:
    label: Text
    type:  textarea
    size:  large

pageselect.css

.form .field.pageselect {
  margin-right: -20px; }

.form .field.pageselect select {
  display: block;
  margin-top: -2px;
  width: 100%;
  margin-bottom: 5px; }

pageselect.php

<?php
  global $site;
  $pages = (isset($path) ? $site->pages->find($path)->children() : NULL);
?>

<select name="<?php echo $name ?>">
  <option value="">Please select a page...</option>
  <?php foreach($pages AS $page): ?>
  <option<?php if($page->uid() == $value) echo ' selected="selected"' ?> value="<?php echo h($page->uid()) ?>"><?php echo h($page->title()) ?></option>
  <?php endforeach ?>
</select>