Popup update question...

[Chad McWilliams]

Say I have a screen named 'entry':

*a
*b
*c

That I use, while in input processing, with popup update -,"entry",a

The processing does nothing but displays the total of a and b in c.  Is
there anyway, after entering a and b, to have show the value of c?  I'm
assuming that updates to the field, after the popup is established, aren't
displayed (since I couldn't get it to).  Is there anyway to accomplish this?

-Chad McWilliams