<div class='container' style='height:1500px; background-color: #f2f2f2'>

  <div  class="dropdown">

  <button class="btn btn-primary dropdown-toggle" type="button" data-mdb-toggle="dropdown"

          data-mdb-auto-close='false'

          aria-expanded="false">

    Dropdown form

  </button>

  <div class="dropdown-menu" style="width: 320px">

    <form class="px-4 py-3">

<select multiple class="select" data-mdb-filter="true">

  <option value="1">One</option>

  <option value="2">Two</option>

  <option value="3">Three</option>

  <option value="4">Four</option>

  <option value="5">Five</option>

  <option value="6">Six</option>

  <option value="7">Seven</option>

  <option value="8">Eight</option>

  <option value="9">Nine</option>

  <option value="10">Ten</option>

</select>

    </form>

    <div class="dropdown-divider"></div>

    <a class="dropdown-item" href="#">New around here? Sign up</a>

    <a class="dropdown-item" href="#">Forgot password?</a>

  </div>

</div>

</div>