try to correct appdi install probel (cf https://github.com/ActiveState/appdirs/issues/89)
<div class="modal-mask diff-panel" v-show="display">
<p class="pull-right close-btn" @click="close"> <i class="fa fa-close"></i> </p>
<slot name="header"></slot>
<slot name="content"></slot>
<slot name="footer"></slot>
</div>