Current controls are undocumented (selecting a rectangle on the graph zooms, hitting the "Reset Graph" link resets to the default) and are also a bit limited. Better controls should be made, and documented on the page.

Controls can perhaps follow the overview-graph style presented on http://people.iola.dk/olau/flot/examples/zooming.html, with deselecting (on either graph) resetting the graph as the current "Reset Graph" button does.