'Crop Tree' is one of the actions available in the Node Context Menu.
To crop the tree in the Visualizer View:
In the complex tree of the Visualizer View, select a specific target node which you want to see the hierarchical relation structure for.
Right-click the node to call the context menu and select 'Crop tree'.
Now only the selected relation structure is displayed.
Two buttons appear in the top left-hand corner:
Start
Click to display the full Visualizer View tree again.
The selected crop
Click to have the cropped relation structure displayed.
When you add more crops, you can toggle among them and have them displayed immediately in the workspace. You can remove the unnecessary crops by clicking the cross icon in the button.