Description
Because people tend not to really agree on how syntax should be highlighted, and there's also potential problems in perception[1], it would be "nice" to have an option to alternate between different syntax highlighting themes.
Search.cpan.org has a similar feature, although its rarely used or even known about because the UI hides it right at the bottom of the page.
http://search.cpan.org/~ether/Moose-2.1403/lib/Moose/Manual/Concepts.pod#COPYRIGHT_AND_LICENSE
My initial suggestion would be to render a very transparent gear of some kind in the upper right corner of a code section, becoming opaque when hovered over, which gave a menu of choices with regards to syntax highlighting.
Granted a determined user could simply inject a custom user stylesheet, but that's rather non-trivial and challenging from a users perspective.
1: ie: not everyone perceives colour the same, and not all displays render colour contrast the same way, have you ever had 2 different screens from different manufacturers side by side, ever tried getting them to look the same? Ugh. And its not just a case of "Make more contrast" to fight low contrast display issues, sometimes you want less contrast because it could be too bright for you or something like that.