One difficulty I'm encountering in studying the structure of Graphics objects is that I have not yet found a way to print or display such structurestructures that isare sufficiently general.
The FullForm of Graphics objects can be huge and extremely difficult to take in visually. I have tried to deal with this using Shallow, but with only limited success, because I find that "the interesting bits" in a Graphics not always occur at the same depth.
It's a chicken-and-egg problem: to write a function that displays such structure in a useful way, I need to understand what such structure could be. But gaining this understanding is precisely what I'm trying to do here!
In case it matters, I'm primarily interested in examining the structure of Graphics objects generated, directly or indirectly, by plotting commands such as Plot, ListPlot, etc.