ToolbarItemProps

The toolbar's buttons, one exported component per tool.

They are components rather than a data list so a caller can compose its own bar out of exactly the tools it wants — <DrawToolbarItem /> <EraserToolbarItem /> — while each button keeps the behaviour that makes it correct: it reads the tool from the UI tool list, so it disappears when the tool is not registered, follows an override's relabelling, and shows itself as pressed when its tool is the current one.