I switch between installer projects, sometimes several times a day. Each project has it's own set of source directories for the content of the installer. Path Variables are saved for each AI project and manually loaded - which is prone to forgetting which causes problems.
It would be very helpful to have the option to define a Path Variables file, the path being stored in the project file, for a project. When that project is loaded it's Path Variables are also loaded. Any time a Path Variable is changed in this case it would be automatically saved to the Path Variables file when the project file is saved.
Command-line definitions would override file-based definitions.