mne.viz.Brain modernization

[payamsash]

Describe the new feature or enhancement

working with mne.viz.Brain GUI, I think we can significantly improve it:

• colorbar currently shows numbers with no context, also we can improve the font and size
• background color can only be chosen when initiating Brain, we could also add str color options (in the docs says tuple (int, int, int))
• better Help dialog
• when an annot is selected we could click on or select a parcel and see the extract_label_time_course signal
• maybe highlighting (a) parcel(s)
• show vertex coordinate and camera orientation when hovering mouse
• better foci visualization
• better trace viewer
• most of the args in the mne.viz.Brain are missing in the GUI
• more keyboard shortcuts
• collapsable panels
• ...

I'm happy to open PRs, but I would like to first see your opinions, tnx @larsoner @drammock @wmvanvliet

Describe your proposed implementation

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Describe possible alternatives

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Additional context

No response

[welcome]

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[larsoner]

I agree with all of those bullets! It could use some improvements. @payamsash I would say go ahead and make those changes in batches of whatever size you think is reasonable to review+merge. Like colorbar + bgcolor could probably be one (too small on their own and almost as easy to review jointly as separately).

For the hover stuff, you can look at as a starting point #13931 (but it's possible there are cleaner implementation paths!). This is maybe related to what you mean by "highlighting a parcel"

[wmvanvliet]

I’m excited for improvements to Brain. Although I also must point out the tradeoff between adding even more complexity to an already complex class and the impact of the a new feature. For example, I don’t see much value in being able to the background color with a GUI. The colorbar improvements I completely agree with. The trace view can be improved in that it behaves a bit odd when you add more traces and resize the window: the whitespace i becomes very inconsistent. Also be qware of what may already supported (such as string background color names?)