The blackboard doesn’t show up on my retina system.
Changing the following in EDITOR_Graph.cs fixes this::
Line 450 (Screen.width reports back double the width you expect for editor GUI positions) blackboardRect.x = Screen.Width - 350;
Change to blackboardRect.x = EditorGUIUtility.currentViewWidth - 350;
You might want to check more uses of Screen.width/height throughout the code to accommodate retina screens correctly.
Ahhh this helped me; thanks for the fix! I thought I was going crazy not seeing my blackboard on my graphs on my Macbook Pro in contrast with when I’m working on my main machine.