I see the problem: there is only one IDLE icon for all users, so you need the env var to customize for each user, which you cannot use. Staying with the python install directory, as before, should be better.  We never got any complaints about that.  But the new install locations are more problematical.

I have also thought of adding an new startup option, but it should only apply if IDLE is started with the ICON.  When started at the command line, it should start at the current directory of the console, as it does now, so '.' refers to that directory.  Ironically, a current directory of .../system32 would be a good indicator.  I need to see what is in sys.argv after the different start methods.

This issue is currently only for Windows. I don't know what happens on other systems or whether they could stand improvement.