The Overview pane, as shown in the following screenshot, displays an overall overview of the current diagram displayed in the middle pane.

• Click and hold the left mouse button to move the highlighted block to the desired area within the diagram, the display in the middle pane changes accordingly.
• Click the left mouse button and use your mouse wheel to zoom in and out the area currently highlighted on the overview diagram.

Two options are available to help increase performance:

• Right click on the overview diagram and choose Hide interiors to only display the outlines of the nodes.
  

• Right click on the overview diagram and choose Hide links to hide the relationships between the entities.