Earlier quoted context omitted.
Are you aware that the use case here is simulating a mouse? Focus switching is not enough.
Ah, I mixed it up with another tool, sorry. This one looks like a small feature in a compositor and not an external tool, really. I guess it would take 100-200 LoC to implement in GNOME Mutter.
Excuse me for being blunt. I don't know if you understand how shitty of a design you advocate. Solid designs do not require modifying core components to write application level features the original authors did not envision.