Steps to reproduce:
1. Download and open project "FadeExperiment"
2. Open scene "Fade/Samples/UI"
3. Play the scene
4. Click the "Push Button"

Actual result:
Sometimes scene view not rendering fade in/out effect wherever the scene or game view window would be placed on screen.

Expected result:
Scene view should render fade in/out effect wherever the scene or game view window would be placed on screen.

Notice when scene view is dragged to other position everything starts to render correctly in scene view. See the attached gif image "UIResponsive.gif" made with 5.3.2p4 version. Also changing rendering modes from Direct3D to OpenGL doesn't solve this bug.

Additional information:
Game view not rendering as scene view in 5.3.2p4 version, but in 5.4.0b8 version it renders correctly. See the attached gif image "UINot.gif" made with 5.3.2p4 version.

Reproduced with: 5.2.3p2, 5.3.2p4, 5.4.0b7, 5.4.0b8