This class maps keyboard events to semantic tree-navigation intents
via the TreeKeyboardDelegate interface. All mutable state
and structural knowledge lives in the delegate — the handler is a
pure key → intent mapper.
Instantiate it once and call handleKeydown from the host
component's (keydown) binding.
Handled keys
Key
Action
ArrowDown
Move cursor down (Shift extends selection)
ArrowUp
Move cursor up (Shift extends selection)
ArrowRight
Expand node, or move cursor down if already expanded
ArrowLeft
Collapse node, or move cursor to parent if collapsed
Enter
Activate the cursor node
Home
Move cursor to first node (Shift extends selection)
End
Move cursor to last node (Shift extends selection)
Keyboard-navigation handler for the tree-view.
This class maps keyboard events to semantic tree-navigation intents via the TreeKeyboardDelegate interface. All mutable state and structural knowledge lives in the delegate — the handler is a pure key → intent mapper.
Instantiate it once and call handleKeydown from the host component's
(keydown)binding.Handled keys
ArrowDownArrowUpArrowRightArrowLeftEnterHomeEndEscape