It seems, I 'm missing something obvious. This is overwriting - what I mean is the syntax for appending (for example: what a windows shell with "set PATH=%PATH%;my_lovely_path" does). Supports this ini file the concept of variable expanding?

no. if you are expert in NSIS scripting, the code is apparently there https://github.com/winpython/winpython/blob/master/portable/launcher.nsi (line 206 to 216)

the Winpython.ini doesn't support expanding, but the new 'student' method would do for you #262 (comment)

(or see todays builds with #268)

Just use the '(student)' icons and change what you don't like in "env_for_student.bat"

I could try complexify further the nsis scripts, but I'm now rather going on the opposite route:

• there is too much complexity in WinPython due to this 'intermediate' technology,
• I whish to reduce it to the minimum and move the logic part to Windows or Python scripts.

I was hoping to exploit the changed PATH w/o using any batch file or similar (in my case to locate some CUDA tools for theano, but this has been solved by utilizing .theanorc).
In the long run though, I agree - the KISS approach is very likely the better choice.

ok. I keep the issue open as I try to rework and simplify this part, yet making it more flexible.

The new configuration and icon system works with winpython.ini like that:
""""
[debug]
state = disabled
[environment]
PATH = %PATH%;my_lovely_cuda;
""""
(if all goes well and changes made do work on windows 10 too)

solved by #272