Sorry, I wasn't aware there was sound. Yes, I can add Ctrl-PgUp and Ctrl-PgDn to navigate to the previous/next folder. Isn't that used for another purpose? That's used for the Previous / Next tab in Chrome, as I see.
I use Firefox, and you are right, Ctrl-PgUp and Ctrl-PgDn are for navigating the tabs. Where in the Tiger code is the keyboard handling implemented? Is that code I can change too? So I can look for my self which shorcuts works. Thanks a lot.