title: v-menu attach not working inside vuetify datatable header filter
body: <p><strong>Steps to reproduce</strong></p>
  
  <blockquote>
    <p>In the codepen there are two different datepicker used, when data is
    present the datepicker is showing as expected, if the table is empty
    while filtering, datepicker hides inside datatable</p>
  </blockquote>
  
  <p><strong>Expected Behavior</strong></p>
  
  <blockquote>
    <p>The datepicker should be showing outside the footer instead of hides
    inside the table</p>
  </blockquote>
  
  <p><strong>Actual Behavior</strong></p>
  
  <blockquote>
    <p>When attach is used it should be sticky to the datepicker input box,
    so that when horizontal scrolling happens, datepicker will also scroll
    along with input box.</p>
    
    <p>At the same time, when no data is present in table both select
    dropdown options and datepicker hides inside the table. Tried the
    z-index for footer as well as datepicker. It didn't worked . Is this a
    bug or is there any other way to handle this case</p>
  </blockquote>
  
  <p><strong>Reproduction Link</strong></p>
  
  <blockquote>
    <p><a href="https://codepen.io/chansv/pen/XWmamRP?editors=1000" rel="nofollow noreferrer">https://codepen.io/chansv/pen/XWmamRP?editors=1000</a></p>
  </blockquote>
  
  <pre><code>&lt;div id="app"&gt;
    &lt;v-app id="inspire"&gt;
      &lt;v-data-table
        :headers="headers"
        :items="desserts"
        :items-per-page="5"
        class="elevation-1"
        hide-default-header
      &gt;
        &lt;template v-slot:header="{ props }"&gt;
          &lt;th v-for="(head, index) in props.headers" :key="index"&gt;&lt;div&gt;{{head.text}}&lt;/div&gt;
            &lt;div v-if="index != 1 &amp;&amp; index != 2"&gt;
              &lt;v-select attach :items="items" placeholder="select with attach"&gt;&lt;/v-select&gt;
            &lt;/div&gt;
            &lt;div style="position: relative;"&gt;
              &lt;div v-if="index === 1" id="foo" style="position: absolute;"&gt;
              &lt;v-menu
                      attach="#foo"
            ref="menu"
            v-model="menu"
            :close-on-content-click="false"
            :return-value.sync="date"
            transition="scale-transition"
            offset-y
            min-width="290px"
          &gt;
            &lt;template v-slot:activator="{ on }"&gt;
              &lt;v-text-field
                v-model="date"
                label="Picker with attach"
                prepend-icon="event"
                readonly
                v-on="on"
              &gt;&lt;/v-text-field&gt;
            &lt;/template&gt;
            &lt;v-date-picker v-model="date" no-title scrollable&gt;
              &lt;v-spacer&gt;&lt;/v-spacer&gt;
              &lt;v-btn text color="primary" @click="menu = false"&gt;Cancel&lt;/v-btn&gt;
              &lt;v-btn text color="primary" @click="$refs.menu.save(date)"&gt;OK&lt;/v-btn&gt;
            &lt;/v-date-picker&gt;
          &lt;/v-menu&gt;
              &lt;/div&gt;
            &lt;/div&gt;
            &lt;div v-if="index === 2" &gt;
              &lt;v-menu
            ref="menu1"
            v-model="menu1"
            :close-on-content-click="false"
            :return-value.sync="date"
            transition="scale-transition"
            offset-y
            min-width="290px"
          &gt;
            &lt;template v-slot:activator="{ on }"&gt;
              &lt;v-text-field
                v-model="date1"
                label="picker without attach"
                prepend-icon="event"
                readonly
                v-on="on"
              &gt;&lt;/v-text-field&gt;
            &lt;/template&gt;
            &lt;v-date-picker v-model="date1" no-title scrollable&gt;
              &lt;v-spacer&gt;&lt;/v-spacer&gt;
              &lt;v-btn text color="primary" @click="menu1 = false"&gt;Cancel&lt;/v-btn&gt;
              &lt;v-btn text color="primary" @click="$refs.menu1.save(date1)"&gt;OK&lt;/v-btn&gt;
            &lt;/v-date-picker&gt;
          &lt;/v-menu&gt;
            &lt;/div&gt;
          &lt;/th&gt;
        &lt;/template&gt;
      &lt;/v-data-table&gt;
    &lt;/v-app&gt;
  &lt;/div&gt;
  
  
  th {
    min-width: 250px;
  }
  
  new Vue({
    el: '#app',
    vuetify: new Vuetify(),
    data () {
      return {
        date: new Date().toISOString().substr(0, 10),
      menu: false,
        date1: new Date().toISOString().substr(0, 10),
      menu1: false,
        items: [
          "dessert",
          "calories",
          "iron",
          "fat"
        ],
        headers: [
          {
            text: 'Dessert (100g serving)',
            align: 'start',
            sortable: false,
            value: 'name',
          },
          { text: 'Calories', value: 'calories' },
          { text: 'Fat (g)', value: 'fat' },
          { text: 'Carbs (g)', value: 'carbs' },
          { text: 'Protein (g)', value: 'protein' },
          { text: 'Iron (%)', value: 'iron' },
          { text: 'Calories', value: 'calories' },
          { text: 'Fat (g)', value: 'fat' },
          { text: 'Carbs (g)', value: 'carbs' },
          { text: 'Protein (g)', value: 'protein' },
          { text: 'Iron (%)', value: 'iron' },
        ],
        desserts: [],
        desserts1: [
          {
            name: 'Frozen Yogurt',
            calories: 159,
            fat: 6.0,
            carbs: 24,
            protein: 4.0,
            iron: '1%',
          },
          {
            name: 'Ice cream sandwich',
            calories: 237,
            fat: 9.0,
            carbs: 37,
            protein: 4.3,
            iron: '1%',
          },
          {
            name: 'Eclair',
            calories: 262,
            fat: 16.0,
            carbs: 23,
            protein: 6.0,
            iron: '7%',
          },
          {
            name: 'Cupcake',
            calories: 305,
            fat: 3.7,
            carbs: 67,
            protein: 4.3,
            iron: '8%',
          },
          {
            name: 'Gingerbread',
            calories: 356,
            fat: 16.0,
            carbs: 49,
            protein: 3.9,
            iron: '16%',
          },
          {
            name: 'Jelly bean',
            calories: 375,
            fat: 0.0,
            carbs: 94,
            protein: 0.0,
            iron: '0%',
          },
          {
            name: 'Lollipop',
            calories: 392,
            fat: 0.2,
            carbs: 98,
            protein: 0,
            iron: '2%',
          },
          {
            name: 'Honeycomb',
            calories: 408,
            fat: 3.2,
            carbs: 87,
            protein: 6.5,
            iron: '45%',
          },
          {
            name: 'Donut',
            calories: 452,
            fat: 25.0,
            carbs: 51,
            protein: 4.9,
            iron: '22%',
          },
          {
            name: 'KitKat',
            calories: 518,
            fat: 26.0,
            carbs: 65,
            protein: 7,
            iron: '6%',
          },
        ],
      }
    },
  })
  </code></pre>