Maintain frame when file externally edited

[complexpoint]

See, for example, this thread:

Try to maintain folding state over modified text

As TaskPaper documents are plain text files, folding state can only be stored in extended attributes of a file, or in Apple’s user interface preservation API. The retention or loss of extended attributes, and the contexts in which each occurs, depends more on operating system design, and on the behaviour of other applications, than on the design of TaskPaper. As I understand it, TP discards the folding state, if the document has been changed externally. It’s actually not TaskPaper that disc…