My book Create Simple GUI Applications with Python & Qt5 has been updated! New chapters on the Model View architecture and custom widgets.
Syntax highlighting is more than just eye candy. It can turn a block of impenetrable code into a simple grok (although it has it's limits). To boost the usability of our code guides on this site we wanted to implement nice clear syntax highlighting of our hacks. Code samples are already marked up with markdown syntax so an extension to this is the obvious choice.
Django ships with it's own comments contrib app that provides commenting on arbitrary models. However this is a flat-comment system which doesn't allow replying to comments. An app called django-threadedcomments exists but has not been updated for a number of versions and is broken. Other alternatives are less flexible than the Django commenting system itself.