How to get location of the element after it was clicked?

Question

I have HTML element(span) the changes it's location.When I click HTML element(span) I need to get the HTML element(span)'s location.

Here is html:

<span class="btnFlyout" id="btn4" style="width: 52px; cursor: pointer; border: 1px solid rgb(240, 240, 240);" 
                                                                        onmouseover="HoverButton('btn4', null)" 
                                                                        onmouseout="LeaveButton('btn4', '')" 
                                                                        onclick="OpenFlyout('cell4', 4, event)">
  <span class="txtFlyout" style="left: 4px;"> measure </span>
    <img class="arrowFlyout" src="../stdicons/icon_menuarrow.gif" style="left: 32px;" width="16px" height="16px" hspace="2" vspace="2">
  </span>

Here is onclick event:

  function OpenFlyout(xpos, tbItemIndex, e)
  {

  }

How can I get HTML element(span) location in OpenFlyout function?