Change mouse icon to hourglass with HTML refresh?

I have an HTML viewer that calls a WebRFC based on the value of a field in my flavor.  The update of the HTML viewer takes a few seconds and I would like the mouse icon to change to the hourglass while it's waiting.  The problem is that I'm refreshing the HTML viewer from a script button (which is executed after the user enters a value in the field and hits enter), but the script button doesn't know when the viewer has completed updating.  Any ideas would be greatly appreciated.

FYI - I'm using Personas 2.0 SP2.

Thanks,

Todd