Have ability to show read-only fields on screens

I'd like to be able to edit screens and show a field, yet not let it be editable. For example, I want to set a policy here that certain fields, once created, can never be changed (such as description and original estimate). Yet when editing a bug (or on other screens, like assign-to), I want those fields to still show up so the user has some context.

For implementation, I was thinking something really simple. The screen editor has a table with Position, Name, and Remove. This feature could be implemented by just adding another column of checkboxes after Name called Read-Only. Then the screen renderer can decide whether or not to make something editable by checking this flag.