The overview window is available on the bottom right corner of the Graph in both view and edit mode.
Click and drag the rectangle within the overview window to move your viewing window.
You can also click anywhere within the overview window to center the rectangle to the clicked location.
To collapse or expand the window, click on the arrow on the left side of the Overview Window
To zoom in using the overview window, resize the viewing window by clicking and dragging the bottom right corner of the rectangle