Electron.
I have been using the Mac for a long time and I can't recall ever seeing a prompt like this when I ⌘Q an app:
Putting aside the thirstiness of asking for an app to remain running in the background, despite it consuming 1.8 GB of RAM in idle state, "Close" does not mean “Quit" in Mac parlance, and the Cancel button should be on the left.
@gruber That's the kind of craft and attention to detail I want from the people who have all my chat service credentials.