How to reproduce:
# Open HUB;
# Create 3D(HDRP) project;
# Create visual effect graph in the "Project" window (Create->Visual Effects-> Visual Effect Graph);
# Drag it to the "Hierarchy" window;
# Select it in the “Hierarchy” window;
# Go to “Inspector” window and click “Edit” in the “General” section;
# Verify, that VFX window opens and it displays graph and blackboard is displayed by default on top;
# Go to “Hierarchy” window and delete your created VFX;
# Go to “Project” window and delete VFX asset too;
# Close the project and save the changes;
# Open the same project again.

Expected result: 
# "No Asset" window shouldn't be displayed in this case, because it is empty (all VFX were deleted).
# If "No Asset" window should be displayed, so in this case "Blackboard" button should be enabled that user could hide it from his screen.

Actual result: "No Asset" window is presented. Blackboard window by default displayed on top. And its button is disabled (there is no opportunity to remove it from the screen).

Reproducible with: 10.10.0 (2020.3.41f1), 12.1.7 (2021.3.12f1), 13.1.8 (2022.1.21f1),  14.0.3 (2022.2.0b12), 15.0.1 (2023.1.0a16).