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(...

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