Hi Mike,
Actually there is a way to do what you want (specifically) but since that's the wrong thing to do in this case, I'm not gonna tell you
. ( Well, ok, it involves overriding the _jsBodyOnLoad method in the web handler.)
However what you are doing is equivalent to putting the following inside the body somewhere;
<script>setTimeout('TimeoutWarning()', 900000);</script>
And since you want that on every page, then it seems to make sense to put it into the header, or footer procedure.
Cheers
Bruce