Change Popup Location

I have the following html code on my page. I have moved my linked table links to the far left of the page instead of being on the left. When i place my mouse over the link it is being displayed far off to the right. How can i modify the line below to force it to display in the middle of the screen or someother location. <img src='https://asprunner.com/forums/file.php?topicimage=1&fieldname=question&id=8516&image=1&table=forumtopics' class='bbc_emoticon' alt=':huh:' />
{if $useAJAX} onmouseover="RollDetailsLink.showPopup(this,'Shipment_detailspreview.asp'+this.href.substr(this.href.indexOf('?')));" onmouseout="RollDetailsLink.hidePopup();" {/if}>Shipment</A> </TD>