I observed we won't be able to identify fieldname typos in an expression if used field is marked as hidden.(A field can be hidden using hideprefix script statement or if a field is tagged 'hidden' in the script).
Expression editor should color incorrect field name in 'red' color or somehow differentiate between unavailable field and the hidden field. I use my set expression indicators hidden by using underscore prefix and sometimes unwanted typos were leaked thru because expression editor didn't help to identify the mistake while editing the expression.


Thanks,
Digvijay