Hi,
how can I make a field read-only based on another custom field value?
For example, I have 2 custom fields: "reviewed" and "effort".
I want the following:
when "reviewed" is empty, "effort" field is editable
when "reviewed" is non-empty, the "effort" field is a read-only field.
I believe it can be done by using behaviors but not sure how 
thanks!