pgadmin3 has the feature that when you selected a table trigger in the object browser panel, it would connect the trigger to the trigger function and allow you to see the function directly from the trigger. That seems to be missing in pgadmin4. Now, in order to view the function, you have to go to the trigger functions section of the object browser. That makes the process of trigger -> trigger function awkward.
Can this pgadmin3 feature be added to pgadmin4?
The feature request for the same has already been logged.