The Left Toolbar displays the Nodes buttons, and the Active Node's context toolbar.
The top section of the Left Toolbar displays the Node buttons. ( See: [Node] for more info)
The buttons section of the Left Toolbar is used by the Active Node's to display buttons and controls. Each node decides what button to add to the left toolbar (if any).
Toggle Show Graph, New Project, Open Project, Save Project, Undo, Redo.
Shapes Node Left Toolbar