LinDistro SlipSystem Installer uses FileSystem.squashfs files generated by penguins-eggs Linux Remastering Tool. We have build a yad + bash script that;
1. User picks icons in a yad --icons window (large images are desktop icon launchers)
2. Script copies users custom theme and module files
3. Script sets selected theme in /etc/calamares/settings to match User Selection
4. User clicks INSTALL button and Calamares launches with USER select theme.