So how can you disable it?
The web page will now reload automatically and return you to your inbox.
The Google Hangouts chat window will now be hidden.
Gmail: How to Hide Google Chat (Hangouts)
The Google Hangouts chat window in Gmail can be an annoying distraction if you just want to check your email in peace. So how can you disable it? First of Learn how to remove Google Chat (Hangouts) from the right pane of the Gmail window.
