Simple enough, it would seem, but it turns out not to be - mainly due to the fact that the View can\'t possibly know which way through Model and Controller you got there. Regard
I don't know about ASPX, but there are a couple of problems we encountered building this:
When the user gets their password wrong, and loops-round the Login page to have another go, the Target must still be preserved.
We also decided to preserve POST variables to a page that then required the just-in-time login