• increase fiducial picking performance (ENH: Coreg GUI #9689 (comment))
• add support for the project_eeg parameter
• add support for the scale_by_distance parameter
• add support for the mark_inside parameter
• console/status_bar idea to add to the UI whatever is printed in the terminal
• display dist estimation in mm.
• add units to UI (Omit more explicit message)
• display axes
• add tooltips as much as possible on widgets
• add support for the scaling parameters (WIP,ENH: new coreg gui features (part 3) #10117)

Bonus territory:

• checkbox for the MEG helmet
• add a slider to control transparency
• add a button to save the fiducials (Passing trans to mne.gui.coregistration() should automatically derive the MRI fiducials #10208 (comment))
• rename "Transform" groupbox into "HEAD <> MRI Transform"
• find a better name for the "Digitization Source" section (which could be confusing)
• show a dialog to save if trans is not saved (Coreg GUI should suggest to save fiducials and trans if not saved during interactive session #10236)
• add a prompt check name already exists "overwrite or not"

• add legend to plot alignment / coreg to see what colored points are etc.
• add support for (qdarkstyle) dark theme
• 📁 icon for file button widgets (instead of "Load")
• multiple threads should block window exit
• add support for object_fit='contain' and object_position='top' (ipywidgets) (How to get the correct event position when object_fit='contain'? Kitware/ipyvtklink#35, How to obtain the coordinates of a click on the image when object_fit='contain'? mwcraig/ipyevents#71)

• add support for the guess_mri_subject parameter (YAGNI)
• add support for the head_inside parameter (YAGNI)
• Update Coregistration() to require parameters (https://mne.discourse.group/t/mne-coreg-based-on-ctf-data/3022/4)
• make the sections collapsible (ipywidgets)
• Decouple GUI code from model (suggested in WIP: Generate subject fiducials #6693 (comment), done in MRG,ENH: Refactor coreg/traits classes #9516)
• Build a coreg GUI using pyvista (done in ENH: Coreg GUI #9689)

• the parameter spin boxes force 2 updates consecutively even though only one interaction is done
• multi-line labels are not supported (ipywidgets)
• Qt crashes during _configure_status_bar() (Windows)
• the app is abnormally slow at loading FIFF (Windows)
• inconsistent behaviour of checkbox layout (ipywidgets)
• the status bar does not support dark theme (qt) (Change CoregistrationUI status bar text color to black #10238 (comment))
• the spin boxes are not updated during ICP with scaling (MNT: _plot_glyphs slow on Windows #10377 (comment))
• the DigPoints are displayed with unlocked fiducials when switching subjects (MRG: Rework CoregistrationUI fiducial I/O widgets & add save button #10242 (comment))
• all HSPs become marked as inside the head surface on certain scaling values (WIP,ENH: some coreg features and fixes #10224 (comment))
• the app hangs when loading trans (ipywidgets)