I committed my changes to the dev source tree to include the Pasti support for Hatari.
This is the first open source version of an STX decoder in an emulator, work based on docs collected by Dr CoolZic, ppetari and sarnau, as well as from my own disassembling of pasti.prg.
This means STX support for Linux, OSX and even Android

This is no official pasti from its author Ijor, but hopefully it should work with all images (I tested 100-200 of them) and in case some STX files are not working, it should be fixable

You can compile the sources for linux / osx or get some prebuilt windows binaries here http://antarctica.no/~hatari/latest/windows/ (use "hatari.exe" and you will also need to put a tos.img file in the downloaded directory).
Please test and report any possible problem before Hatari 1.8 release, including TOS version and RAM config, also check the game works under Steem too (for many STX games, it's recommended to use TOS 1.02 or 1.04)
Nicolas