var delm = new MyWindow(500, 50, 'delete_messages', 'deleteMessages', 'delm');

function openDeleteMessages()
{
    if(delm.window != 'null') {
        delm.close();
    }
    delm.aj_parameters = $('deleteMessages').serialize();
    delm.reload = true;
    delm.open();
}
function deleteMessages()
{
    $('deleteMessages').submit();
}