Graham The_Netter There are probably better ways of doing this now using xtscript but I created this method about 5 years ago before xtscript was created
basically in your form you have hidden inputs
<input type="hidden" name="hide1" value=""/>
and if required
<input type="hidden" name="hide2" value="!--"/>
then your hidden code to show after submit is like
<{_$hide1|!--}div>some text or code</div{_$hide1|--}>
or the reverse
<{_$hide2|}div>some text or code</div{_$hide2|}>