Bug introduced in 8 or earlier and persisting through 11.3

The following behavior is stably reproduced with versions 8.0.4, 10.4.1, 11.0.1 and 11.1.1 on Windows 7 x64.

Set the NotebookDynamicExpression:

 NotebookDynamicExpression :> Refresh[nb = EvaluationNotebook[], UpdateInterval -> .1]]

Evaluate Dynamic[nb]:



Everything is as expected so far. Now just select the code Dynamic[nb] and copy it via Ctrl+C. Here is what becomes:


By evaluating nb you occasionally can get the hidden NotebookObject:



This object isn't listed in Notebooks[]:



What happens here? From where comes the hidden NotebookObject? Why nb periodically switches between the two NotebookObjects? Is it a bug?

  • $\begingroup$ It seems to be a clipboard notebook, not sure why it inherits NotebookDynamicExpression. $\endgroup$
    – Kuba
    May 10, 2017 at 18:29
  • $\begingroup$ @Kuba Yes, NotebookGet@ClipboardNotebook[] returns a Notebook with the NotebookDynamicExpression. Then it is certainly a bug, right? $\endgroup$ May 10, 2017 at 18:51
  • $\begingroup$ I'd agree, definitely worth reporting $\endgroup$
    – Kuba
    May 10, 2017 at 18:55
  • $\begingroup$ Similar pb with OSX and MMA 11.1.1 : i don't get the "blinking/switching" dynamic object, but the nb command returns NotebookObject[16]. I have recently played with NotebookDynamicExpression and Refresh and observed some strange similar switching effects in Dynamic but not very reproducible, i gave up. $\endgroup$
    – SquareOne
    May 10, 2017 at 23:27
  • $\begingroup$ @SquareOne Does NotebookGet@ClipboardNotebook[] return a Notebook expression containing the NotebookDynamicExpression? $\endgroup$ May 11, 2017 at 0:12


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