Be more informative when asking for login
If a service triggers a popup containing a login request, the Webathena page should probably say why the user is looking at it. (The post-login page should still prompt like it does now... unless we put all that information on the login screen and say that providing your password is consenting to giving the ticket, in which case we only show the post-login prompt if the user already had only a TGT.)
Also, do we really need a separate HTML file for this? Can we just pass parameters to index.html?
Yeah, I was thinking it maybe should have been the same file. One nuisance is that we need to distinguish pages opened as RPC calls and pages navigated to normally. WinChan.onOpen actually throws an exception if you navigate to the page normally; in the IE case, it needs to locate its relay iframe. It's probably harmless, but we shouldn't be registering an onOpen on pages that aren't RPC calls. It's expected that the page will shortly be closed when you call cb there.
We could maybe distinguish them with location.hash. Like webathena.scripts.mit.edu/#request_ticket_v1.