> Yes, what I did was not import this module by default. Instead I added
> mne.gui which could be imported when needed, so you could
>
> >>> from mne import guy
> >>> gui.HeadMriCoreg(...

ok makes sense as long as import mne does not break if Traits and co
are not available.

> But I was going to ask how to handle this dependency. Since the whole
> module works with it I wanted to avoid the indent of defining the class in a
> function. an alternative wouldbe to have functions, say mne.fit_mri_to_head
> which then imports mne.transforms.coreg_gui when it's called

I like the idea of a single function call to start the coreg.