I'm using a facebox to display a form inside a lightbox, nothing too exciting (just a couple of datepickers, some textboxes and a checkbox). However, I'm having issues with the postbacks, whenever I post back from the facebox it adds a ',' to the start of the input (so "rabbit" becomes ",rabbit") Now, I saw that there was the same issue with the modalpopup extender from the ajaxcontroltoolkit, so I assume it's a common issue.

Can anyone either explain why this is happening, or tell me how to fix it? provide a decent way of fixing this? I have actually done it, and it works very nicely, but I don't really want to answer my own bounty question so someone else give it a go!

Cheers, Ed

EDIT

See attached answer for a correct solution (I fixed this eventually but didn't want to ruin the bounty question so left the answer until afterwards).