How can I recieve a notification when a PDF document is modified?

Q: I'm wondering if there is a way to receive notification when a PDF
has changed. I know that you can manually check the PDFDoc.IsModified
property, but I would like to automatically receive notification when
the document is changed via an event, ie 'DocumentChangedEvent'. Is
there anything of this sort available? Essentially I have a form that
opens the document with a 'Save' button set to disabled. Only when
the document gets modified do I want to make the save button
'Enabled'.
-----
A: At the moment there is no callback/even that will let you know when
a document is modified. To implement this in your code you could
either check IsModified() after a code block that could potentially
modify the document. Alternatively you could use a slow timer to
periodically check the state of IsModified property.