Sidekick20 and catridge loading problems

[OldWer]

I tried loading cartridges with multiple files, but multiple selection does not work for me - the space key does nothing in the browser. I wonder what I am doing wrong?

Then I found out I could make .crt files that Sidekick20 recognizes, using the cartconv.exe tool from the Vice emulator. When I convert multiple catridge files in this way, they load OK, and some play OK, but many of them crash to basic or exhibit other strange behavior. I think this must be Sidekick20's fault, because they run fine in Vice. Is there any chance for a better cartridge support?