What is the proper way to open a Demonstration in Mathematica so that the code is visible and can be evaluated from the Evaluation menu, as though I had created it myself?
Explanation: When I download a demonstration's .nb file and open it in Mathematica, I typically find myself looking at some elementary instructions for authors. I find this puzzling, because at that particular moment, I am trying to be a viewer or user of the demonstration, not one of its authors.
With the .nb file open, I can usually get the demonstration to function, but I usually cannot see the code. In the past I have managed to experiment with various menu commands to eventually reveal the code, but in a recent attempt I was unsuccessful, specifically in dealing with a file called TurtleGraphics-author.nb.
Using another approach, in the past I have clicked a link on the demonstration's web page to "preview" the author code. I then see some code, but exactly what "preview" subset it may be I am not sure. At that point I can click another screen button to show the initialization code, but again I'm not clear whether I am then seeing all of the code or still only some of it.
Whatever code I do see in this "preview" is shown in a small font which lacks both contrast and resolution. The code cannot be selected or copied, except as an image.
All this confuses me. In trying to reuse the author's demonstration code, am I doing something prohibited?