Use renderer for edit page.

edit.php

@@ -78,7 +78,5 @@ if ($mform->is_cancelled()) {
 $PAGE->set_heading(format_string($course->fullname));
 $PAGE->set_title(get_string('pluginname', 'enrol_apply'));
 
-echo $OUTPUT->header();
-echo $OUTPUT->heading(get_string('pluginname', 'enrol_apply'));
-$mform->display();
-echo $OUTPUT->footer();
+$renderer = $PAGE->get_renderer('enrol_apply');
+$renderer->edit_page($mform);

renderer.php

@@ -34,6 +34,13 @@ class enrol_apply_renderer extends plugin_renderer_base {
         echo $this->footer();
     }
 
+    public function edit_page($mform) {
+        echo $this->header();
+        echo $this->heading(get_string('pluginname', 'enrol_apply'));
+        $mform->display();
+        echo $this->footer();
+    }
+
     public function manage_form($table, $manageurl) {
         echo html_writer::start_tag('form', array('id' => 'enrol_apply_manage_form', 'method' => 'post', 'action' => $manageurl->out()));