A new update is here!
Among other things, I've implemented your suggestion for highlighting owned and wishlisted games (haven't got around to discounted yet) in the catalogue and other people's wishlists for easier viewing.
I've also added the option to remove / hide people from you chat contacts list. It automatically removes anyone you have blocked but also adds an option to the dropdown menu on each contact to remove that person from the list.
If they send you a new message they will be re-added to the list.
To stop hiding previously hidden contacts you have to manually edit the JSON object in the options but it's just a case of removing their name from the list.
And finally I've added a 'Chat Transcript' button into the chat options bar which creates a pop up with your entire chat history in it (because scrolling up and down the chat to find particular things can be a nightmare).
It's still a bit of a work in progress and needs some formatting and styling but serves it's purpose for now.
Enjoy, and let me know if you find any bugs or have any questions.