This script adds a blackout button to Special:Chat and all AjaxRC-enabled dynamic pages. In Special:Chat, the button appears to the left of the wordmark (at the top left). In other pages, the button appears to the right of the global navigation (in the header).
the author, and then posted here for the convenience of others who might find it useful.
You might find this script useful if:
You want to play a game while monitoring a dynamic page such as Chat or Wiki Activity in the background.