Steps to repro:

1. Open Unity on OSX;
2. Create new project and scene;
3. Click File -> Build&Run;
4. In the Build Settings ensure that you're in Mac, PC, Linux Standalone mode;
5. Click Build&Run button;
6. Collapse opened Player Configuration window;
7. Click on Player configuration icon in OSX Dock panel.

Actual result:
Player Configuration window isn't shown again. Also user it's unable to close Player configuration window by right clicking on tray icon and clicking close (once the window has been collapsed).
That brings inconsistency within the product, because on Windows you can expand Player configuration window from tray icon. See attached actual.png screenshot.

Expected result:
User should be able to expand/close Player configuration window on OSX by clicking tray icon in OSX Dock panel.

Workaround is to expand Player configuration window by selecting it in pages panel (located at the right side of the Dock). See attached actual.png as well.

Notes:
- Reproducible in: 5.4.0b6, 5.4.0b5, 5.3.2f1, 5.3.1f1.
- Reproducible in OSX 10.11.3;
- Not reproducible on Windows 10.