Ok, I'm modifying this post because it seems like it is kinda working.
I'm on facebook that is calling a .aspx in the Facebook iframe. When the user clicks on a button, I do:
FormsAuthentication.SetAuthCookie("theusername", True)
Response.Write("<script>window.open('mypage.aspx','_blank');</script>")
when mypage.aspx shows up, the user is not logged in. However, if I edit mypage.aspx and put the formsauthentication.setauthcookie directly there in the page_load it works. So why can't the application set it.
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