- Disable row and cell navigation and selection
- Introduce custom selection and navigation handling based on groups
- Select a group by hitting 'Enter'
- Edit a group by hitting 'Space' (only available for data groups)
- Support copying data from the groups using Ctrl+C and Ctrl+X
- Only allow single selection for now

- Improve keyboard navigation to skip over non-existing groups
- Copy should always use the focused group and not the selected one
- Fix issue of losing focus when submitting a data edit
- Support pasting values in data cells without going into edit mode
- Improve styling in all themes
-- Avoid orange focus outline and use same as tree for visibility
-- Selected cells get their colors overwritten
-- Slightly increase padding between two data groups