Technically all they have to do is open up the edit screen and then they can edit their message indefinitely as long as that screen remains open (regardless of any admin settings). Will the following code override any other settings and at least include an "edited by" message after each edit?
Code:
// -----------------------------
// Are we marking this as edited
$editdate = "";
if ( $markedit ) {
$editdate = $html -> get_date();
}
replace the above with:
// -----------------------------
// Are we marking this as edited
$editdate = $html -> get_date();