create the "activesetup project" that builds the executable which will be responsible to write the OPEN HKCU key.
start refactoring custom action project to extract the logic for setting the HKCU Open key
create the custom actions that will set the HKCU for the current user using directly the binary .exe file ActiveSetupCommand.exe. Prepare the custom action for setting the ActiveSetup command (cannot be done directly in wix).
finishing the wix structure: the custom actions that set the HKLM key containing the active setup stubPath for install/uninstall are symetric for the sake of simplicity.
refactor customactions, implement fake logic (only log parameters)
ActiveSetupExeName was incorrect
minor refactorings
use [INSTALLFOLDER] for the custom actions, path to .exe cannot be relative.
Implement logic for the executable files invoked by both active setup and wix.