ie8 click on button trigger select’s ondbclick, could do it?

ie8 click on button then trigger select’s ondbclick, could do it? actually,that is a ie8 watermark mask penetrate problem

button.attachEvent('onclick',function(e){
    var currentDom = e.srcElement;
    var point = document.elementsFromPoint(e.clientX, e.clientY);
    if(point.tagName.toLowerCase() == 'select') {
        point.focus()
        // trigger select's dbclick function
        .....
    }
})

<select ondbclick="changeSelct(this);">
  <option>a</option>
  <option>b</option>
</select>

so anyone give me some suggestions