Game Window can not be resized by dragging down in 2 by 3 layout

Steps to Reproduce:

1. Create a new project
2. Change layout to 2 by 3
3. Select Game Window
4. Hover mouse to the Border of the Game Window
5. Drag downwards

Expected Result: Game Window should resize

Actual Result: Game Window is not getting resized

Note: Once it dragged upwards then downwards also works fine

Reproducible on: 2019.3.0a10

Working Fine on: 2019.3.0a9, 2019.2.0b10, 2019.1.0f2