To Reproduce:
-Create a new unity project
-Download and install the Visual Effect Graph package (Window -> Packagemanager-> Visual Effect Graph)
-Create a visual effect gameobejct (GameOebject -> Visual Effects - > Visual Effect)
-Create a new VFX asset (Project window right-click -> Create->Visual Effects-> Visual Effect Graph)
-Select the asset
-Open the VFX graph window (Window-> Visual Effects-> Visual Effect Graph)
-Put your cursor towards the bottom-right of the window called new VFX with a plus
-Try to resize the window

Expected result:
The window boundary should scale with the content of the window

Actual result:
The window boundary remains static but the content is able to scale

Platforms tested:
Windows and MAC

Versions affected:
2019.3.0f1, 2019.3.0f2, 2020.1.0a15