Both Windows and macOS have added PiP mode to their OS. If you are using Gnome Shell, here’s how you can enable picture-in-picture mode in Gnome Shell.
The Fishery is a plugin repository for Fish Shell (a replacement shell for Bash that has a lot of features going for it). Check it out.
The GNOME shell introduced user interface changes that altered the way many Linux users now manage windows. Here are five GNOME shell extensions that seamlessly expand on the functionality of GNOME 3 without ignoring its new design conventions.