OK, so just one line of code in just one file locks it for life.
As I understand it, there is no way to ever get rid of the 'blue dot" even if you take out the one line of code. I tried it and I could not get the file back to 'virgin' status. Even if one space is entered somewhere your system knows it was chaned and you can't un-change it (especially if you forget where you put that one space or blank line!)
So, assuming I'm right above, once you make a single change... even to just test something, you can never ever update that theme again... not auto... not manual.
Is that right?