Graph view is not centered when opening a local subgraph for the first time

Steps to reproduce:

1. Download and import the attached "gtk-subgraph-centering.unitypackage"
2. Create and open a graph (Assets > Create > Graph > Basic Graph)
3. Create a node
4. Create a subgraph from the node
5. Open the subgraph

Actual results: The contents of the subgraph is positioned somewhere north-west of the center of the window

Expected results: The contents of the subgraph is positioned in the center of the window

Tested on (OS): MacOS