add parameters to button's POST request

[iwuser]

>>..But now that I've tried, it didn't work...

I guess that makes sense as since a session doesn't exist the controls aren't really initialized by IW yet.  Maybe adding a ScriptEvents->Values["onClick"] = "document.cookie='NAME=VALUE;...'"; to the submitting button would force the cookie to exist as the new session starts.

Nope, did not work either: IW sheds all cookies when it establishes a new session. I see 2 POST's in a row, 1st contains this cookie in the request, but the response sets a new session cookie only and so in the 2nd POST it's all forgotten, only the new session cookie is set. And then my code kicks in and it sees nothing.