Focus stealing has been an issue in windowed multi-tasking environments from the beginning. It's certainly been an issue in all macOS/OS X versions I've used since I started in 2011.
Agreed. Since sharing input between multiple applications (and the OS services) is its primary role, you would think that UI designers would have “thou shalt not steal focus” as a commandment, but that is not the case.
My latest version of the problem is with Ubuntu Gnome. Upgrade software and, later, you will be interrupted with a pop-up window to enter your system password. Not only is this an interruption, I’m always doubtful that this is the system asking for a sudoer password!
UIs, in my experience, are very bad at handling “interrupts”. Sorry, my dad designed chips, so I use that hardware term when talking about notifications and other times another application needs to notify or get the input from user. Personally, I’d have the UI change the color/texture of the system menubar/taskbar and wait for the user to click it.
I've been using windowed multi-tasking environments since 1986. Never been a problem for me (SunOS -> Solaris -> Linux). I rely very, very, very much on focus-follows-mouse.
My latest version of the problem is with Ubuntu Gnome. Upgrade software and, later, you will be interrupted with a pop-up window to enter your system password. Not only is this an interruption, I’m always doubtful that this is the system asking for a sudoer password!
UIs, in my experience, are very bad at handling “interrupts”. Sorry, my dad designed chips, so I use that hardware term when talking about notifications and other times another application needs to notify or get the input from user. Personally, I’d have the UI change the color/texture of the system menubar/taskbar and wait for the user to click it.