use yii\helpers\Html;
$listView = new ListView(['dataProvider' => $dataProvider, 'itemView' => '_item', 'layout' => "{summary}\n{items}\n{pager}\n"]);
$listView->sorter = ['options' => ['class' => 'mail-sorter']];
?>
<h1>Email messages</h1>
<div class="row">
<div class="col-lg-2">
<?php
echo Html::button('Form filtering', ['class' => 'btn btn-default', 'onclick' => '$("#email-form").toggle();']);
?>
</div>
<div class="row col-lg-10">
<?php
echo $listView->renderSorter();
?>
</div>
</div>
<div id="email-form" style="display: none;">
<?php
$form = ActiveForm::begin(['method' => 'get', 'action' => ['/debug/default/view', 'tag' => Yii::$app->request->get('tag'), 'panel' => 'mail']]);
?>
<div class="row">
<?php
echo $form->field($searchModel, 'from', ['options' => ['class' => 'col-lg-6']])->textInput();
?>
<?php
echo $form->field($searchModel, 'to', ['options' => ['class' => 'col-lg-6']])->textInput();