Gmail popout windows don't work.

[davekuhar]

Clicking the button to pop a message out into a new window results in an empty window.

The same thing happens if you click on a link you've embedded into a message to test it.

[davekuhar]

This problem extends to clicking on macOS Sierra notifications – they pop open an empty window.

[sivaramsi]

Yes, it's a known bug. Thanks for reporting :)

[davekuhar]

You got it. I'll report more bugs when I find them, if you'd like!