12 points
- Hover effects, you often want to respond to the user hoving their mouse somewhere, for instance showing a tooltip.
- Battery/network saving, a site can pause animations or reduce update requests when the window is inactive.
- I cant really think of a good use for this one these days, it was something browsers had in the 90s (not just readonly, websites could move your browser window where they wanted for a while). Maybe its kept for backwards compatibility.
3 points
That explains it. Thank you and @iamkindasomeone@feddit.de for the replies!