discourse/app/assets/javascripts/admin/templates/groups-bulk.hbs

<div class='groups-bulk'>
  <p>{{i18n "admin.groups.bulk_paste"}}</p>

  <div class='control'>
    {{textarea value=users class="paste-users"}}
  </div>

  <div class='control'>
    {{combo-box filterable=true content=groups value=groupId none="admin.groups.bulk_select"}}
  </div>

  <div class='control'>
    {{d-button disabled=buttonDisabled
               class="btn-primary"
               action="addToGroup"
               icon="plus"
               label="admin.groups.bulk"}}
  </div>
</div>