This may be a duplicate of https://bugs.chromium.org/p/chromium/issues/detail?id=898608 - I don't know enough of the terminology to be sure.

Chrome Version       : 72.0.3596.0
OS Version: OS X 10.13.6
URLs (if applicable) : https://chat.google.com
Other browsers tested:
  Add OK or FAIL after other browsers where you have tested this issue:
     Chrome (not shortcut window): OK

What steps will reproduce the problem?
1. Go to https://chat.google.com
2. Add as shortcut
3. Open chrome://apps
4. Right click chat app -> open in window
5. Open the app
6. In a chat with a user, try to drag and drop an image to share it.

What is the expected result?

The image is uploaded and can be sent.

What happens instead of that?

The drag and drop is not accepted, the chat window appears to ignore it.


Please provide any additional information below. Attach a screenshot if
possible.

UserAgentString: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_13_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/72.0.3596.0 Safari/537.36