<bmx-graph-overview>
A small picture of a whole bmx-graph, with a box showing the part in view.
Zoom into the graph with the buttons or Ctrl and the wheel; the box in the overview shows where you are. Drag the box, or click anywhere in the overview, to move there. Tab to the overview and use the arrow keys.
Every property, event and method: https://docs.binarymission.co.uk/webcomponents/bmx/bmx-graph-overview.html