UserAgent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/56.0.2924.87 Safari/537.36

Steps to reproduce the problem:
1. Inject an iframe onto a webpage
2. Inject another html element (such as a div) on a webpage. Position the div so that it is over the iframe but has a higher z-index. The element must also be invisible, no background color, no border, no opacity. Add some kind of event listener, such as onmousedown or onclick to this invisible div.
3. When you click or try and interact with the invisible element, nothing happens. The events will not fire. It appears that even if the invisible element has a higher z-index and should be available to interact with, it doesn't work. If the element is not placed above an iframe then it still behaves as expected. If the invisible element becomes visible (given a background color or border or some other attribute) users are able to interact with it again.

What is the expected behavior?
Invisible html elements placed over an iframe should trigger an on click or other event listener. 

What went wrong?
I used to be able to click an invisible html element placed over an iframe and have it trigger an on click or on drag event. The invisible handle serves as a way for users to drag the injected iframe around the screen.

Did this work before? Yes 56.0.2924.87 I think, the latest update (56.0.2924.110) seems to have caused it 

Chrome version: 56.0.2924.87  Channel: stable
OS Version: Mint
Flash Version: