Purpose

This pull request improves the accessibility of the document tree by allowing keyboard users to:

• See the action menu (e.g. “more options” and “create sub-document” buttons) when navigating with Tab.
• Open a sub-document by pressing Enter when the corresponding tree item is focused.

issue : 1160

Sub-document navigation is accessible, we can now navigate and open sub-docs using the keyboard.

Implementation note:
A small useTreeItemKeyboardActivate hook listens for Enter or Space only when the current node has focus (node.isFocused). This compensates for a limitation in react-arborist, which doesn't trigger any "activate" behavior on keyboard events.

For the action buttons (like ... or +) that appear when a tree item is focused:
By default, react-arborist uses a "roving tabindex", so these buttons are not reachable with Tab.
To fix this and make them keyboard-accessible:
I added a hook useActionableMode and some algo.

Proposal

• Add :focus-within on the tree item wrapper to show the contextual action menu when a child receives focus.
• Add :focus-visible outlines on buttons inside the menu to improve visible feedback.
• Add aria-label attributes to make icon-only buttons screen reader accessible (e.g. “More options”, “Add chil document”).
• Add keyboard support for the icon buttons using onKeyDown to handle Enter and Space.