[jQuery] change title of the dialog by setData

How do I change dialog title after it was created?
I try to do
$('#dlg').data('title', 'new title') or $('#dlg').data('dialog.title',
'new title') but its not working
the only way I get run the setData event is
using .data('setData.dialog', 'something in here') but then key for a
function is setData.
any ideas?
I'm using jquery-1.2.3
and ui - 1.5b2
thanks