The diagram is composed of smart-mimic-symbol elements, so a symbol on the diagram is the same live object as a standalone symbol: it has a tag, a state and a reading, and it raises its own click events. The canvas adds placement, connection routing, the viewport and the layout.
Click a symbol to select it. Drag the empty canvas to pan and use Ctrl+wheel to zoom. The diagram is a single tab stop: press Tab to focus it and use the arrow keys to move between symbols.