listen to MapExtentChangedEvent in workflow html5 viewer

Hi,

I made a workflow that gets the map extent and uses it to form a url to a external viewer. The url is part of a list of urls that are displayed in a form. Once clicked another viewer will be opened  with the same extent. This all work well. But once the workflow is opened the form is displayed in the right-hand-side container of the viewer. It is still possible to change the extent of the map. I want to dynamically update my url. I tried to do this following this example: http://support.geocortex.com/use-workflow-to-listen-and-react-to-viewer-events. I included a ListenForExternalEvent (MapExtentChangedEvent) and a CollectExternalEventArgs for this event.  If I place this event listener in the workflow before I built the form it works but waits for the extent to change before it displayes the form. If I use a flowchart and place the event listener after I built the form and point back to the form that was built it never fires. The form seems to be the end-station of the workflow. I do not want to include a button saying "Click here if you changed the extent", of course. Any ideas on how to make this work? 

Best, Tjibbe