Instead of two levels of focus with `focus` and `selected`, use a recursive
level. The components set the one "active" and hbox/vbox/dbox
Co-authored-by: ArthurSonzogni <sonzogniarthur@gmail.com>
- Fix focus in flexbox. This required resetting the focus state at the
beginning of the ComputeRequirement(), because it can now run several
times.
This resolves:https://github.com/ArthurSonzogni/FTXUI/issues/399
- Add Box::Union.
- Add a preliminary implementation of forwarding selected_box from
within the flexbox.
This implement the flexbox elements, following the HTML one.
Built from them, there is also the following elements:
- `paragraph`
- `paragraphAlignLeft`
- `paragraphAlignRight`
- `paragraphAlignCenter`
- `paragraphAlignJustify`
This is a breaking change.
