Module Brr_note_kit.Ui
Graphical user interaction.
Warning. This will definitively break in the future.
Note based GUI toolkit.

XXX.
- A common interface seems to emerge. Can we get rid of the different types and unify the elements under a single type ?
- Provide action refinement. This could be as an optional argument but it's likely you want to do it after. So as *.with_action functions seem better.
- Layout is still painful
module Group : sig ... end
Element groups.
module Label : sig ... end
Labels.
module Button : sig ... end
Buttons.
module Jstr_editor : sig ... end
String editors.
module Value_selector : sig ... end
Value selectors
module Float_selector : sig ... end
Floating point value selector.