Stale file in Eclipse editor

[yaaros]

Hi !!

I have a problem with recognizing stale (out of sync) state in my
editor. I wrote simple editor, using Eclipse UI Forms. Editor got file
as an input and edits text from this file.
And now, how could I recognize that the file is out of sync. When
someone modify it outside application I'd like to know that and could
update/refresh the context in editor.
Anyone has an idea ??

Thanks
Yaaros