Eric Larson

@agramfort Windows is... having trouble with this. Can you write a little test over in the OpenMEEG repo using equivalent files? Or would it help for me to give it...

@agramfort for now I'm inclined to say it only works on windows, and raise an error there if you try to do it. That way we can continue to make...

... and this is painful: ``` 56.70s call mne/forward/tests/test_make_forward.py::test_make_forward_solution_openmeeg[3] ``` but I'm not sure there is much we can do about it :(

... and we have a problem that `comps` is never used here

Looking at the code, I think the best way to handle compensation is with a heavy refactoring of the forward computation code. I could do this at the same time...

Got it to fail on Windows 3.10 pip pre. Let's try with 2.6.0.dev1 from TestPyPi which has OpenMP disabled...

@agramfort do you want to attempt the rebase here or would you like me to do it?

Okay with file-based IO for `_make_openmeeg_geometry` we get on Windows: ``` E PermissionError: [WinError 32] The process cannot access the file because it is being used by another process: 'C:\\Users\\VSSADM~1\\AppData\\Local\\Temp\\openmeeg-io-t2wktag7\\tmp.geom'...

@agramfort feel free to merge if you're happy

To me this is a pretty simple fix to use `_get_trans` like we do elsewhere. It should automatically support everything you want. And then the docstring should be deduplicated /...