UserAgent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_11_4) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/50.0.2661.102 Safari/537.36

Example URL:
https://plnkr.co/edit/uGiMHWiGKquMIcn7NKD7?p=preview

Steps to reproduce the problem:
When a user clicks on an option in a select element, the resulting mouse event either does not fire (OS X), or fires with incorrect clientX and clientY values (Windows and Linux)

The plunkr demo listens for bubbled click events on the body element, and logs their .clientX and .clientY properties to the console.

1. Bring up the developer console/

2. Click on the background, confirm that the clicks are logged and the clientX and clientY properties are correct.

3. Open the select and click on one of the options.

What is the expected behavior?
The browser should recognise the mouse click on the option, and log valid clientX and clientY properties.

What went wrong?
On OS X, the click on the option does not result in a mouse event, therefore is nothing is logged to the console.

One Windows, the click on the option fires an event, but it has negative clientX and clientY properties.

Does it occur on multiple sites: Yes

Is it a problem with a plugin? No 

Did this work before? N/A 

Does this work in other browsers? Yes 

Chrome version: 50.0.2661.102  Channel: stable
OS Version: 
Flash Version: Shockwave Flash 21.0 r0

I believe Linux behaves the same as Windows, but I have not been able to check first-hand.