Viewport buttons on Mac are difficult to open

QA REGRESSION: Yes
WORKING: 2616418
BROKEN: 2623997

In the Mac editor, the Viewport buttons are difficult to open, requiring multiple clicks to keep the list visible.

Update:
QA REGRESSION: Yes
WORKING: 2616418
BROKEN: 2633546

1. Launch UE4Editor.exe QAGame.
2. Click on any of the viewport buttons (Lit, Show, Perspective, etc).