How to reproduce it:
1. Open the user's attached project ("UIToolkit.zip")
2. Load the "SampleScene" scene
3. Enter the Play Mode
4. In the Game view click on the button and notice that it was clicked
5. Click on the top-left brown square and notice that the button wasn't clicked
6. Click on the red overlay that is over the button
7. Observe the button

Expected result: The VisualElement doesn't pass a click event, and the button is not clicked
Actual result: The VisualElement passes a click event, and the button is clicked

Reproducible with: 1.0.0-preview.14 (2020.2.5f1, 2021.1.0b7)
Could not test with: 2018.4.32f1, 2019.4.20f1 (UI Toolkit is not introduced yet), 2021.2.0a5 (due to UI Toolkit's errors)