Thanks, I'm glad it's useful! Thanks also for the suggestions. I uploaded a new version - the status text now shows more information in brackets; including the uncompressed number of bytes in the block, the compressed number of bits in the block, as well as whether it's a CHR (single move-to-front character), or a REF block (reference i.e. offset+length copy) or a RAW block (uncompressed chunk; these are rare).
I've also tried fiddling with some attributes to try and make the visualization more crisp and clear. The boxes are sharper now but the text still seems antialiased unfortunately.
zep was very generous providing the compression code used in PICO-8; I'm just checking he's cool with me sharing before I open source this. I believe the wiki page seems spot on describing the format.