QWebEngineView couldn't handle touch events for html select's popup menus

<select onchange="alert('option changed!');">
<option value="0">V0</option>
<option value="1">V1</option>
<option value="2">V2</option>
<option value="3">V3</option>
</select>

Poup menu items' could not be touched under surface win10 touch screen; while mouse events works fine.
NOTE:
1）Quick nano browser demo works
2）Webengine widgets simple browser do not works, could not show alert box. All select element's popup menu item could not be changed.