Last night, I've committed some long due changes to the MESS GUI software picker. Before, the software picker would work like this:
1. On startup or when a system is selected, it would scan through all software directories and identify all files with certain extensions and also ZIP files. This would block, meaning that if there were a ton of files, the UI would freeze until this is completed.
2. Files would get an icon depending on their extension, or a question mark icon if they were zips.
3. During the idling process, it would open up the ZIPs and give them a new icon based on the extension of the first file in the ZIP.
4. All files would also have their hashes checked, so that the "goodname" information could be identified.
This had a few problems:
1. People did not like the UI locking up for even a half second if many images were present.
2. People were unable to have ZIP files containing multiple images.
I've done a rewrite of the software picker code. After this rewrite, you should be able to place all of your iamges in a single ZIP if you wish. Additionally, the process is fully asynchronous and images loaded and saved while in emulation should not be touched. As with all major changes, there are probably bugs, so I'd like people to try it out so that it can be solid by the time MESS 0.86 comes out.