To reproduce:
- Create a project and a cube
- Go to Preferences and make sure that the box for "Verify Saving Assets"
- Make some changes to the Cube, e.g. add a material and give it a color
- Make sure that the Color Picker window is open and centered on screen (I am on a 13" MacBook Pro)
- Press CTRL+S (or CMD+S)
- Observe that a "Save Assets" window pops up
- Hit "Close" and observe that the Color Picker window closes
- Hit "Close" again and observe that the "Save Assets" window now closes

Expected result: As a user I would expect the "Save Assets" window to close down the first time I hit the "Close" button.