Finding out when actionLink action is completed on the user side

Hi everybody,
I have an actionLink, which action returns the pdf document from the
server. The document is dynamically generated, so it can take few seconds
to deliver it to the user. I want to prevent the user from clicking on the
actionLink multiple times. I can block it in java script after the click
event occurrs, but I don't know how to find out when to unblock it.

Is there a way to find out when the document is received by the user and
then unblock the actionLink? I found one possible solution, but it seems
like an overhead:
http://stackoverflow.com/questions/1106377/detect-when-browser-receives-file-download
Is there a more tapestry way to do it?

Here is the actionLink code:
                                    <t:actionLink
t:id="downloadDocumentAsPdf" context="document.document_id"
                                        target="_blank">
                                        ${message:download.document.as.pdf}
                                    </t:actionLink>