Where is the "spin edit control" referred to in the message box for Database Diagram?
It is referring to “Change the reference depth to display’ in the Toolbar. It has a value of 1 initially. You can change this to 0, so it will not auto-include the tables it has relationships with. The ‘spin edit control’ may be the general name for that type of control.
For more information about the Database Diagram, view SOL102214: How to build an ER diagram in Toad Data Point,which contains a tutorial video for the feature.