[fw-general] encoding problem in ajax request

[info]

Hi,
I am italian and so i use ISO-8859-1 encoding to support accented  
character (à è ì ò ù).

In a controller i use ajaxContext for some actions. In these actions i  
need to apply utf8_decode for all text fields in POST otherwise the  
accented characters become like è à ì ù à in the DB.

How can i fix this? How can i use ajaxContext?

Thanks