Hello Maxime,

thanks you for the patch review!

> Often GUIs have problems with finding icons, could you check whether
> qucs-s works in a pure environment?

I tried to run Qucs-S installed through Guix, like the follows:

--8<---------------cut here---------------start------------->8---
guix shell -D guix
./pre-inst-env guix shell -D --pure qucs-s
qucs-s
--8<---------------cut here---------------end--------------->8---

And all the icons seem to be fine

Although it can be that I don't fully understand what you mean by "pure
environment" in that case.

> Propagation is not very robust (e.g. if run directly from the store with $(guix
> build qucs-s)/bin/the-binary), would it be possible to not propagate this? E.g.,
> if you are propagating it because of not finding a binary, you could use
> substitute* to insert an appropriate absolute file name.

Okay, that's a good point.  I checked the sources for the places where
Qucs-S uses executable paths and added substitutions for that.

I kept NGSpice in "propagated-inputs" because Qucs-S requires it to do
the simulations in runtime.

Also I've added GNU Octave to the "propagated-inputs" and substituted
the path to Octave too.

I tried to run simulations from the examples provided with the Qucs-S
and it seems to me that Qucs-S mostly works as it should.

I should note here that I'm not very good at electronics and such
simulations yet, so you should take what I said above with a grain of
salt indeed.  ;-)

Please check the updated patch.