@rvs: thank you for the info, I've added that to mi link collection.
@Iņigo: Hola
Actually, my plan is to enjoy my DRs as much as possible writing as little code as possible, with the least possible effort, so I'd rather learn whatever I need before trying things like QT or whatever the iRex guys didn't consider. Thank you for the warning.
Currently my only projects (and I won't start real coding very soon) are extending the image viewer so it can handle multiple-image TIFFs (if it's not too difficult I'd extend it to read other multi-image formats and zipped image collections, like .cbzs) and tweaking the browser as I hit its limits with my HTML format for ebooks (hopefully not too much).
@Mackx: thank you for the hint about UDS. Also, it'll be probably very interesting to compare the old PDF stuff and see if we can spot any changes in the sources rvs pointed us to.