Crash on clicking Animation Curve, created using UIElement for Mac OSX

Steps to Reproduce:
1. Open attached Project
2. Click on UIElementsExamples on the Menu bar
3. Select 07_EditorControls
4. Resize the Window to find the Animation Curves
5. Left Click & Right Click on the Curve for 4-5 times

Notes on repro steps :
To effectively reproduce the problem, I had to run Unity and the 07 example from the MacBook Pro screen. It doesn't care where the popup menu appears.

Working with:
2018.1.0f2

Reproduces on:
2018.2.0b7, 2018.2.0b4, 2018.2.0b1, 2018.2.0a5, 2018.2.0a1

Environment:
Only occurring on Mac OSX 10.13

Note:
It works fine on Mac OSX 10.12 and Windows 10