DVT SystemVerilog IDE User Guide
Rev. 19.1.13, 25 April 2019
A diagram is created around a set of relevant classes you specify. For example when you decide to show parents, children or associations by using UML Diagrams - Preferences, it applies only to selected classes. In a diagram the selected classes are colored with yellow fill (see also the UML Diagrams - Legend).
The right list shows the selected classes. Use left/right arrows or double click to select the relevant classes.
You can also add/remove an element to/from the current selection by right clicking on it in the diagram and choosing "Select Type"/"Deselect Type":