Use the Structure view as a Preview, that allows you to get a "10,000-feet" look on a diagram. The shadow area represents the visible part of a diagram. As you zoom in or out, or change shape of the PhpStorm windows, the size of the shadow area changes accordingly.
- Keeping the mouse button pressed, move the shadow area to obtain the desired view.
- Select one or more nodes in diagram, and the corresponding nodes in the Preview are marked dark gray.