It also displays an error when .bal files are read-only. Many source control systems like to have the files set to read only and then when a check-out is done, the source control system will remove the read-only flag. Then when you do a check-in, the read-only flag is turned back on. This is helpful if you forget to do a check-out, the IDE should let you know the file is read-only. This is especially true when the IDE does not integrate with source control.
I have posted this as a bug twice with no response.