How to show a popup div outside the browser window


just like this.
the main window is always focus.

if I use child browser window,the main browser can lose focus when I am editing the child window.
what I need is alway keep the main window is focus,so the popup DIV is one choice .
but I don’t know how to implement outside the main window


What immediately comes to mind is using the same child window method as is used to create menus, but that is for native programming. I don’t know how you could do that in Electron.