Lost focus event

I’m searching to set a pause menu and pause the game when lost the focus of the application but I don’t find a lost focus event.
Is it possible to know when the window lost focus ? How ?

There is a node for this in the Victory Plugin, it is called in focus or something.

I searched but not found inside “VictoryBPLibrary” and typing “focus”.

hmm. I recall reading something about that in the thread.