In my custom .kid template for datagrid I use the following trick:
<?python
def default_geturl(**kw):
return "?" + '&'.join(['%s=%s' % (k,w) for k,w in kw.items()])
geturl = value_of('geturl', default_geturl)
?>
...
<a href="${geturl(order='desc',sortby=col.name)}"><img
src="${std.tg_static}/images/arrow_down.png" border="0"/></a>To change urls dynamically I pass to the template my own geturl function. HTH, Max.

