Do not refresh the whole page when changing subtask status (work in progress)

app/Template/subtask_restriction/popover.php

@@ -0,0 +1,17 @@
+<div class="page-header">
+    <h2><?= t('You already have one subtask in progress') ?></h2>
+</div>
+<form class="popover-form" action="<?= $this->url->href('SubtaskRestriction', 'update', array('task_id' => $task['id'], 'project_id' => $task['project_id'], 'subtask_id' => $subtask['id'])) ?>" method="post">
+
+    <?= $this->form->csrf() ?>
+
+    <p><?= t('Select the new status of the subtask: "%s"', $subtask_inprogress['title']) ?></p>
+    <?= $this->form->radios('status', $status_list) ?>
+    <?= $this->form->hidden('id', $subtask_inprogress) ?>
+
+    <div class="form-actions">
+        <input type="submit" value="<?= t('Save') ?>" class="btn btn-red">
+        <?= t('or') ?>
+        <a href="#" class="close-popover"><?= t('cancel') ?></a>
+    </div>
+</form>