code: func (w *Window) Kill() {
  	xproto.KillClient(w.X.Conn(), uint32(w.Id))
  }
docs: // Kill forcefully destroys a client. It is almost never what you want, and if
  // you do it to one your clients, you'll lose your connection.
  // (This is typically used in a special client like `xkill` or in a window
  // manager.)