Editor crashed on Maximizing and Un-maximizing any window around 20 times using Shift + Space keys.

Steps to Reproduce:
1. Create a new project
2. Hover mouse on any tab and Press Shift + Space

Actual Result:
Editor crashed on Maximizing and Un-maximizing tabs

Reproducible on:
2019.1.0a10

Works on:
2019.1.0a9, 2018.3.0b12, 2018.2.0f2

Environment:
Only on Mac

Note:
1. Sometimes crash occurs on Maximizing/Minimizing window 30 times. The count is not fixed.
2. Refer attached editor log and attached video.