다음은 editor.php 파일을 아래와 같이 수정했습니다..

<div id="kboard-default-editor">
    <form class="kboard-form" method="post" action="<?php echo $url->getContentEditorExecute()?>" enctype="multipart/form-data" onsubmit="return kboard_editor_execute(this);">

        <?php $skin->editorHeader($content, $board)?>
        <?php foreach($board->fields()->getSkinFields() as $key=>$field):?>
            <?php echo $board->fields()->getTemplate($field, $content, $boardBuilder)?>
        <?php endforeach?>
        <div class="kboard-control">
            <div class="left">
                <?php if($content->uid):?>
                    <a href="<?php echo $url->getDocumentURLWithUID($content->uid)?>" class="kboard-default-button-small"><?php echo __('Back', 'kboard')?></a>
                    <a href="<?php echo $url->getBoardList()?>" class="kboard-default-button-small"><?php echo __('List', 'kboard')?></a>
                <?php else:?>
                    <a href="<?php echo $url->getBoardList()?>" class="kboard-default-button-small"><?php echo __('Back', 'kboard')?></a>
                <?php endif?>
            </div>
            <div class="right">
                <?php if($board->isWriter()):?>
                    <button type="submit" class="kboard-default-button-small"><?php echo __('Save', 'kboard')?></button>
                <?php endif?>
            </div>
        </div>
        <textarea name="kboard_content" id="kboard_content"><?php echo $content->content?></textarea>
    </form>
</div>

<?php
wp_enqueue_script('kboard-default-script', "{$skin_path}/script.js", array(), KBOARD_VERSION, true);
?>
<link href="<?php echo $skin_path ?>/assets/quill/quill.snow.css" rel="stylesheet">
<link rel="stylesheet" href="//cdn.quilljs.com/1.3.6/quill.bubble.css">
<script src="//cdn.quilljs.com/1.3.6/quill.js"></script>
<script>
    var quill = new Quill('.kboard-content', {
        theme: 'snow', //  'snow', 'bubble'
    });
    jQuery(".kboard-form").on("submit",function(){
        jQuery("#kboard_content").val( jQuery(".ql-editor").html() );
    });
</script>

음. 글은 먼저 정상적으로 업로드되는데, 글을 수정하면 html 코드가 그대로 노출됩니다.

어떤 부분을 찾아봐야 할지요..

ps. 퀼 에디터도 기본적으로 삽입 가능할런지요^^;